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           Third National Health and Nutrition Examination Survey               
                            (NHANES III), 1988-94                               
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                            Catalog Number 76700                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
        NHANES III Variable Ingredient Data File from the Dietary Recall        
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                December 1996                                   
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                               
                              Table of Contents                                 
                                                                                
                                                                                
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
Guidelines for Data Users. . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
Survey Description . . . . . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
Sample Design and Analysis Guidelines. . . . . . . . . . . . . . . . . .        
                                                                                
Data Preparation and Processing Procedures . . . . . . . . . . . . . . .        
                                                                                
General References . . . . . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
NHANES III Variable Ingredient Data                                             
                                                                                
     General Information . . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
     Data File Index . . . . . . . . . . . . . . . . . . . . . . . . . .        
                                                                                
     Data File Item Descriptions, Codes, Counts, and Notes . . . . . . .        
                                                                                
     Sas Code to Merge Look-up Tables  . . . . . . . . . . . . . . . . .        
                                                                                
                                                                               
                                Introduction                                    
                                                                                
The National Center for Health Statistics (NCHS) of the Centers for Disease     
Control and Prevention (CDC) collects, analyzes, and disseminates data on       
the health status of U.S. residents.  The results of surveys, analyses, and     
studies are made known through a number of data release mechanisms              
including publications, mainframe computer data files, CD-ROMs (Search and      
Retrieval Software, Statistical Export and Tabulation System (SETS)), and the   
Internet (http://www.cdc.gov/nchswww/nchshome.htm).                             
                                                                                
The National Health and Nutrition Examination Survey (NHANES) is a periodic     
survey conducted by NCHS.  The third National Health and Nutrition              
Examination Survey (NHANES III), conducted from 1988 through 1994, was the      
seventh in a series of these surveys based on a complex, multi-stage sample     
plan.  It was designed to provide national estimates of the health and          
nutritional status of the United States' civilian, noninstitutionalized         
population aged two months and older.                                           
                                                                                
Data from NHANES III are being released in five public release data files:      
                                                                                
     NHANES III Household Adult Data File (Catalog Number 77560)                
                                                                                
     NHANES III Household Youth Data File (Catalog Number 77550)                
                                                                                
     NHANES III Examination Data File (Catalog Number 76200)                    
                                                                                
     NHANES III Laboratory Data File (Catalog Number 76300)                     
                                                                                
     NHANES III Dietary Recall Data Files (Catalog Number 76700)                
                                                                                
                                                                                
                                                                                
A table showing the location of the interview and examination components in     
the five NHANES III public release data files follows.                          
                                                                                
                                                                               
Location of the interview and examination components in the five NHANES III     
public release data files                                                       
                                                                                
                                                      Data File                 
                                                                                
                                                                                
               Topic                     | HA  | HY  | EXAM  | LAB | DIET |     
-----------------------------------------+-----+-----+-------+-----+------+     
Sample weights                           |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Age/race/sex                             |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Ethnic background                        |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Household composition                    |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Individual characteristics               |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Health insurance                         |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Family background                        |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Occupation of family head                |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Housing characteristics                  |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Family characteristics                   |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Orientation                              |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Health services                          |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Selected health conditions               |  X  |  X  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Diabetes questions                       |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
High blood pressure and                  |  X  |  .  |   .   |  .  |   .  |     
     cholesterol questions               |     |     |       |     |      |     
-----------------------------------------+-----+-----+-------+-----+------+     
Cardiovascular disease questions         |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Musculoskeletal conditions               |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Physical functioning questions           |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Gallbladder disease questions            |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
                                                                                
                                                                               
Location of the interview and examination components in the five NHANES III     
public release data files (continued)                                           
                                                                                
                                                                                
                                                     Data File                  
                                                                                
                                                                                
               Topic                     | HA  | HY  | EXAM  | LAB | DIET |     
-----------------------------------------+-----+-----+-------+-----+------+     
Kidney conditions                        |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Respiratory and allergy questions        |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Diet questions                           |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Food frequency                           |  X  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Vision questions                         |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Hearing questions                        |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Dental care and status                   |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Tobacco                                  |  X  |  .  |   X   |  .   |   . |     
-----------------------------------------+-----+-----+-------+-----+------+     
Occupation                               |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Language usage                           |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Exercise                                 |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Social support/residence                 |  X  |  .  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Vitamin/mineral/medicine usage           |  X  |  X  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Blood pressure measurement               |  X  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Birth                                    |  .  |  X  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Infant feeding practices/diet            |  .  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Motor and social development             |  .  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Functional impairment                    |  X  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
School attendance                        |  .  |  X  |   .   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Cognitive function                       |  .  |  X  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
                                                                                
                                                                               
Location of the interview and examination components in the five NHANES III     
public release data files (continued)                                           
                                                                                
                                                      Data File                 
                                                                                
                                                                                
               Topic                     | HA  | HY  | EXAM  | LAB | DIET |     
-----------------------------------------+-----+-----+-------+-----+------+     
Alcohol and drug use                     |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Reproductive health                      |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Diagnostic interview schedule            |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Activity                                 |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Physician's examination                  |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Height and weight                        |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Body measurements                        |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Dental examination                       |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Allergy skin test                        |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Audiometry                               |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Tympanometry                             |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
WISC and WRAT                            |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Spirometry                               |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Bone densitometry                        |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Gallbladder ultrasonography              |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Central nervous system                   |  .  |  .  |   X   |  .  |   .  |     
 function evaluation                     |     |     |       |     |      |     
-----------------------------------------+-----+-----+-------+-----+------+     
Fundus photography                       |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Physical function evaluation             |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Fasting questions                        |  .  |  .  |   .   |  X  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
                                                                                
                                                                               
Location of the interview and examination components in the five NHANES III     
public release data files (continued)                                           
                                                                                
                                                      Data File                 
                                                                                
                                                                                
               Topic                     | HA  | HY  | EXAM  | LAB | DIET |     
-----------------------------------------+-----+-----+-------+-----+------+     
Laboratory tests on blood and urine      |  .  |  .  |   .   |  X  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Total nutrient intakes                   |  .  |  .  |   X   |  .  |   .  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Individual foods                         |  .  |  .  |   .   |  .  |   X  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Combination foods                        |  .  |  .  |   .   |  .  |   X  |     
-----------------------------------------+-----+-----+-------+-----+------+     
Ingredients                              |  .  |  .  |   .   |  .  |   X  |     
-----------------------------------------+-----+-----+-------+-----+------+     
                                                                                
                                                                                
Data File Definitions                                                           
                                                                                
HA   -  Household Adult Data File                                               
HY   -  Household Youth Data File                                               
EXAM -  Examination Data File                                                   
LAB  -  Laboratory Data File                                                    
DIET -  Dietary Recall Data Files                                               
                                                                                
                                                                               
This document includes the documentation for the NHANES III Foods Data          
File and also contains a general overview of the survey and the use of the      
data files.  The general overview includes five sections.  The first            
section, entitled "Guidelines for Data Users," contains important information   
about the use of the data files.  The second section, "Survey Description,"     
is a brief overview of the survey plan and operation.  The third section,       
"Sample Design and Analysis Guidelines," describes some technical aspects of    
the sampling plan and discusses some analytic issues particularly related to    
the use of data from complex sample surveys.  The "Data Preparation and         
Processing Procedures" section describes the editing conventions and the        
codes used to represent the data.  The last and fifth section, "General         
References," includes a reference list for the survey overview sections of      
the document.                                                                   
                                                                                
Public Use Data Files for the third National Health and Nutrition               
Examination Survey will also be available from the National Technical           
Information Service (NTIS).  A list of NCHS public use data tapes available     
for purchase from NTIS may be obtained from the Data Dissemination Branch at    
NCHS.  Information regarding a bibliography (on disk) of journal articles       
citing data from all the NHANES and the availability of NHANES III data in      
CD-ROM/SETS software format can be obtained from the Data Dissemination         
Branch(301-436-8500) or by writing to:                                          
                                                                                
Data Dissemination Branch                                                       
National Center for Health Statistics                                           
Room 1018                                                                       
6525 Belcrest Road                                                              
Hyattsville, Maryland 20782                                                     
                                                                                
                                                                                
NTIS can be contacted at:                                                       
                                                                                
NTIS - Computer Products Office                                                 
5285 Port Royal Road                                                            
Springfield, Virginia 22161                                                     
(703) 487-4807                                                                  
                                                                                
Copies of all NHANES III questionnaires and data collection forms are           
included in the Plan and Operation of the Third National Health and             
Nutrition Examination Survey, 1988-94 (NCHS, 1994; U.S. DHHS, 1996).  This      
publication, along with detailed information on NHANES procedures,              
interviewing, data collection, quality control techniques, survey design,       
nonresponse, and sample weighting can be found on the NHANES III Reference      
Manuals and Reports CD-ROM (U.S. DHHS, 1996).  Information on how to order      
this CD-ROM is available from the Data Dissemination Branch at NCHS at the      
address and telephone number given above.                                       
                                                                                
                                                                               
                    GUIDELINES FOR DATA USERS                                   
                                                                                
                                                                                
Please refer to the following important information before analyzing data.      
                                                                                
                                                                                
NHANES III Background Documents                                                 
                                                                                
o    The Plan and Operation of the Third National Health and Nutrition          
     Examination Survey, 1988-94, (NCHS, 1994; U.S. DHHS, 1996) provides an     
     overview of the survey and includes copies of the survey forms.            
                                                                                
o    The sample design, nonresponse, and analytic guidelines documents on       
     the NHANES III Reference Manuals and Reports CD-ROM (U.S. DHHS, 1996)      
     discuss the reasons that sample weights and the complex survey design      
     should be taken into account when conducting any analysis.                 
                                                                                
o    Instruction manuals, laboratory procedures, and other NHANES III           
     reference manuals on the NHANES III Reference Manuals and Reports          
     CD-ROM(U.S. DHHS, 1996) are also available for further information on      
     the details of the survey.                                                 
                                                                                
                                                                                
Analytic Data Set Preparation                                                   
                                                                                
o    Most NHANES III survey design and demographic variables are found only     
     on the Adult and Youth Household Data Files.  In preparing a data set      
     for analysis, other data files must be merged with either or both of       
     these files to obtain many important analytic variables.                   
                                                                                
o    All of the NHANES III public use data files are linked with the common     
     survey participant identification number (SEQN).  Merging information      
     from multiple NHANES III data files using this variable ensures that       
     the appropriate information for each survey participant is linked          
     correctly.                                                                 
                                                                                
o    NHANES III public use data files do not have the same number of            
     records on each file.  The Household Questionnaire Files (divided into     
     two files, Adult and Youth) contain more records than the Examination      
     Data File because not everyone who was interviewed completed the           
     examination. The Laboratory Data File contains data only for persons       
     aged one year and older.  The Individual Foods Data File based on the      
     dietary recall has multiple records for each person rather than the one    
     record per sample person contained in the other data files.                
                                                                                
o    For each data file, SAS program code with standard variable names and      
     labels is provided as separate text files on the CD-ROM that contains      
     the data files.  This SAS program code can be used to create a SAS         
     data set from the data file.                                               
                                                                                
o    Modifications were made to items in the questionnaires, laboratory,        
     and examination components over the course of the survey; as a result,     
     data may not be available for certain variables for the full six years.    
     In addition, variables may differ by phase since some changes were         
     implemented between phases.  Users are encouraged to read the Notes        
     sections of this document carefully for information about changes.         
                                                                                
o    Extremely high and low values have been verified whenever possible,        
     and numerous consistency checks have been performed.  Nonetheless, users   
     should examine the range and frequency of values before analyzing          
     data.                                                                      
                                                                               
o    Some data were not ready for release at the time of this publication       
     due to continued processing of the data or analysis of laboratory          
     specimens.  A listing of those data are available in the general           
     information section of each data file.                                     
                                                                                
o    Confidential and administrative data are not being released to the         
     public.  Additionally, some variables have been recoded to help            
     protect the confidentiality of the survey participants.  For example,      
     all age-related variables were recoded to 90+ years for persons who were   
     90 years of age and older.                                                 
                                                                                
o    Some variable names may differ from those used in the Phase 1 NHANES       
     III Provisional Data Release and some variables included in the Phase 1    
     provisional release may not appear on these files.                         
                                                                                
o    Although the data files have been edited carefully, errors may be          
     detected.  Please notify NCHS staff (301-436-8500) of any errors in        
     the data file or the documentation.                                        
                                                                                
                                                                                
                                                                               
Analytic Considerations                                                         
                                                                                
o    NHANES III (1988-94) was designed so that the survey's first three         
     years, 1988-91, its last three years, 1991-94, and the entire six          
     years were national probability samples.  Analysts are encouraged to use   
     all six years of survey results.                                           
                                                                                
o    Sample weights are available for analyzing NHANES III data.  One of        
     the following three sample weights will be appropriate for nearly all      
     analyses:  interviewed sample final weight (WTPFQX6), examined sample      
     final weight (WTPFEX6), and mobile examination center (MEC)- and           
     home-examined sample final weight (WTPFHX6).  Choosing which of these      
     sample weights to use in any analysis depends on the variables being       
     used.  A good rule of thumb is to use "the least common denominator"       
     approach.  In this approach, the user checks the variables of              
     interest.  The variable that was collected on the smallest number of       
     persons is the "least common denominator," and the sample weight that      
     applies to that variable is the appropriate one to use for that            
     analysis.  For more detailed information, see the Analytic and Reporting   
     Guidelines for NHANES III (U.S. DHHS, 1996).                               
                                                                                
                                                                                
Referencing or Citing NHANES III Data                                           
                                                                                
o    In publications, please acknowledge NCHS as the original data source.      
     For instance, the reference for the NHANES III Laboratory Data File        
     is:                                                                        
                                                                                
     U.S. Department of Health and Human Services (DHHS).  National Center      
     for Health Statistics.  Third National Health and Nutrition                
     Examination Survey, 1988-1994, NHANES III Laboratory Data File (CD-ROM).   
     Public Use Data File Documentation Number 76200.  Hyattsville, MD.:        
     Centers for Disease Control and Prevention, 1996.  Available from          
     National Technical Information Service (NTIS), Springfield, VA.            
     Acrobat.  PDF format; includes access software:  Adobe Systems, Inc.       
     Acrobat Reader 2.1.                                                        
                                                                                
o    Please place the acronym "NHANES III" in the titles or abstracts of        
     journal articles and other publications in order to facilitate the         
     retrieval of such materials in bibliographic searches.                     
                                                                                
                                                                               
                         SURVEY DESCRIPTION                                     
                                                                                
                                                                                
The third National Health and Nutrition Examination Survey (NHANES III) was     
the seventh in a series of large health examination surveys conducted in        
the United States beginning in 1960.  Three of these surveys, the National      
Health Examination Surveys (NHES), were conducted in the 1960's (NCHS, 1965;    
NCHS, 1967; NCHS, 1969).  In 1970, an expanded nutrition component was added    
to provide data with which to assess nutritional status and dietary             
practices, and the name was changed to the National Health and Nutrition        
Examination Survey (Miller, 1973; Engel, 1978; McDowell, 1981).  A special      
survey of Hispanic populations in the United States was conducted during        
1982-1984 (NCHS, 1985).                                                         
                                                                                
The general structure of the NHANES III sample design was similar to that       
of the previous NHANES.  All of the surveys used complex, multi-stage,          
stratified, clustered samples of civilian, noninstitutionalized                 
populations.  NHANES III was the first NHANES without an upper age limit; in    
fact, the age range for the survey was two months and older.  A home            
examination option was employed for the first time in order to obtain           
examination data for very young children and for elderly persons who were       
unable to visit the mobile examination center (MEC).  The home examination      
included only a subset of the components used in the full MEC examination       
since it would have been difficult to collect some types of data in a home      
setting.  A detailed description of design specifications and copies of the     
data collection forms can be found in the Plan and Operation of the Third       
National Health and Nutrition Examination Survey, 1988-1994 (NCHS, 1994; U.S.   
DHHS, 1996).                                                                    
                                                                                
NHANES III was conducted from October 1988 through October 1994 in two          
phases, each of which comprised a national probability sample.  The first       
phase was conducted from October 18, 1988, through October 24, 1991, at 44      
locations.  The second phase was conducted from September 20, 1991, through     
October 15, 1994, at 45 different locations.  In NHANES III, 39,695 persons     
were selected over the six years; of those, 33,994 (86%) were interviewed       
in their homes.  All interviewed persons were invited to the MEC for a          
medical examination.  Seventy-eight percent (30,818) of the selected persons    
were examined in the MEC, and an additional 493 persons were given a special,   
limited examination in their homes.                                             
                                                                                
Data collection began with a household interview.  Several questionnaires       
were administered in the household:  Household Screener Questionnaire,          
Family Questionnaire, Household Adult Questionnaire, and Household Youth        
Questionnaire.                                                                  
                                                                                
At the MEC, an examination was performed, and five automated questionnaires     
or interviews were administered:  MEC Adult Questionnaire, MEC Youth            
Questionnaire, MEC Proxy Questionnaire, 24-Hour Dietary Recall, and Dietary     
Food Frequency (ages 12-16 years).  The health examination component            
included a variety of tests and procedures.  The examinee's age at the time     
of the interview and other factors determined which procedures were             
administered.  Blood and urine specimens were obtained, and a number of tests   
and measurements were performed including body measurements, spirometry,        
fundus photography, x-rays, electrocardiography, allergy and glucose            
tolerance tests, and ultrasonography.  Measurements were taken of bone          
density, hearing, and physical, cognitive, and central nervous system           
functions.  A physician performed a limited standardized medical examination    
and a dentist performed a standardized dental examination.  While some of the   
blood and urine analyses were performed in the MEC laboratory, most analyses    
were conducted elsewhere by contract laboratories.                              
                                                                                
                                                                               
A home examination was conducted for those sample persons aged 2-11 months      
and aged 20 years or older who were unable to visit the mobile examination      
center.  The home examination consisted of an abbreviated version of the        
tests and interviews performed in the MEC.  Depending on age of the sample      
person, the components included body measurements, blood pressure,              
spirometry, venipuncture, physical function evaluation, and a questionnaire     
to inquire about infant feeding, selected health conditions, cognitive          
function, tobacco use, and reproductive history.                                
                                                                                
                                                                               
               SAMPLE DESIGN AND ANALYSIS GUIDELINES                            
                                                                                
                                                                                
Sample Design                                                                   
                                                                                
The general structure of the NHANES III sample design is the same as that       
of the previous NHANES.  Each of these surveys used a stratified, multi-stage   
probability design.  The major design parameters of the two previous NHANES     
and the special Hispanic HANES, as well as NHANES III, have been previously     
summarized (Miller, 1973; McDowell, 1981; NCHS, 1985; NCHS, 1994).  The         
NHANES III sample was designed to be self-weighting within a primary            
sampling unit (PSU) for subdomains (age, sex, and race-ethnic groups).  While   
the sample was fairly close to self-weighting nationally for each of these      
subdomain groups, it was not representative of the total population, which      
includes institutionalized, non-civilian persons that were outside the          
scope of the survey.                                                            
                                                                                
The NHANES III sample represented the total civilian, noninstitutionalized      
population, two months of age or over, in the 50 states and the District of     
Columbia of the United States.  The first stage of the design consisted of      
selecting a sample of 81 PSU's that were mostly individual counties.  In a      
few cases, adjacent counties were combined to keep PSU's above a minimum        
population size.  The PSU's were stratified and selected with probability       
proportional to size (PPS).  Thirteen large counties (strata) were chosen       
with certainty (probability of one).  For operational reasons, these 13         
certainty PSU's were divided into 21 survey locations.  After the 13            
certainty strata were designated, the remaining PSU's in the United States      
were grouped into 34 strata, and two PSU's were selected per stratum (68        
survey locations).  The selection was done with PPS and without                 
replacement.  The NHANES III sample therefore consists of 81 PSU's or 89        
locations.                                                                      
                                                                                
The 89 locations were randomly divided into two groups, one for each phase.     
The first group consisted of 44 and the other of 45 locations.  One set         
of PSU's was allocated to the first three-year survey period (1988-91) and      
the other set to the second three-year period (1991-94).  Therefore,            
unbiased estimates (from the point of view of sample selection) of health and   
nutrition characteristics can be independently produced for both Phase 1        
and Phase 2 as well as for both phases combined.                                
                                                                                
For most of the sample, the second stage of the design consisted of area        
segments composed of city or suburban blocks, combinations of blocks, or        
other area segments in places where block statistics were not produced in       
the 1980 Census.  In the first phase of NHANES III, the area segments were      
used only for a sample of persons who lived in housing units built before       
1980.  For units built in 1980 and later, the second stage consisted of sets    
of addresses selected from building permits issued in 1980 or later.  These     
are referred to as "new construction segments."  In the second phase, 1990      
Census data and maps were used to define the area segments.  Because the        
second phase followed within a few years of the 1990 Census, new construction   
did not account for a significant part of the sample, and the entire sample     
came from the area segments.                                                    
                                                                                
                                                                               
The third stage of sample selection consisted of households and certain         
types of group quarters, such as dormitories.  All households and eligible      
group quarters in the sample segments were listed, and a subsample was          
designated for screening to identify potential sample persons.  The             
subsampling rates enabled production of a national, approximately               
equal-probability sample of households in most of the United States with        
higher rates for the geographic strata with high Mexican-American               
populations.  Within each geographic stratum, there was a nearly                
equal-probability sample of households across all 89 stands.                    
                                                                                
Persons within the sample of households or group quarters were the fourth       
stage of sample selection.  All eligible members within a household were        
listed, and a subsample of individuals was selected based on sex, age, and      
race or ethnicity.  The definitions of the sex, age, race or ethnic             
classes, subsampling rates, and designation of potential sample persons         
within screened households were developed to provide approximately              
self-weighting samples for each subdomain within geographic strata and at the   
same time to maximize the average number of sample persons per sample           
household.  Previous NHANES indicated that this increased the overall           
participation rate.  Although the exact sample sizes were not known until       
data collection was completed, estimates were made.  Below is a summary of      
the sample sizes for the full six-year NHANES III at each stage of selection:   
                                                                                
Number of PSU's                                  81                             
Number of stands (survey locations)              89                             
Number of segments                               2,144                          
Number of households screened                    93,653                         
Number of households with sample persons         19,528                         
Number of designated sample persons              39,695                         
Number of interviewed sample persons             33,994                         
Number of MEC-examined sample persons            30,818                         
Number of home-examined sample persons           493                            
                                                                                
More detailed information on the sample design and weighting and estimation     
procedures for NHANES III can be found in the Plan and Operation of the         
Third National Health and Nutrition Examination Survey, 1988-94 (NCHS, 1994;    
U.S. DHHS, 1996) and in the Analytic and Reporting Guidelines: Third National   
Health and Nutrition Examination Survey (NHANES III), 1988-94 (U.S. DHHS,       
1996).                                                                          
                                                                                
Analysis Guidelines                                                             
                                                                                
Because of the complex survey design used in NHANES III, traditional            
methods of statistical analysis based on the assumption of a simple random      
sample are not applicable.  Detailed descriptions of this issue and possible    
analytic methods for analyzing NHANES data have been described earlier (NCHS,   
1985; Yetley, 1987; Landis, 1982; Delgado, 1990).  Recent analytic and          
reporting guidelines that should be used for most NHANES III analyses and       
publications are contained in Analytic and Reporting Guidelines (U.S. DHHS,     
1996).  These recommendations differ slightly from those used by analysts for   
previous NHANES surveys.  These suggested guidelines provide a framework to     
users for producing estimates that conform to the analytic design of the        
survey.  All users are strongly urged to review these analytic and reporting    
guidelines before beginning any analyses of NHANES III data.                    
                                                                                
                                                                               
It is important to remember that this set of statistical guidelines is not      
absolute.  When conducting analyses, the analyst needs to use his/her           
subject matter knowledge (including methodological issues) as well as           
information about the survey design.  The more one deviates from the original   
analytic categories defined in the sample design, the more important it is to   
evaluate the results carefully and to interpret the findings cautiously.        
                                                                                
In NHANES III, 89 survey locations were randomly divided into two sets or       
phases, the first consisting of 44 and the other of 45 locations.  One set      
of PSU's was allocated to the first three-year survey period (1988-91) and      
the other set to the second three-year period (1991-94).  Therefore, unbiased   
national estimates of health and nutrition characteristics can be               
independently produced for each phase as well as for both phases combined.      
Computation of national estimates from both phases combined (i.e., total        
NHANES III) is the preferred option; individual phase estimates may be          
highly variable.  In addition, individual phase estimates are not               
statistically independent.  It is also difficult to evaluate whether            
differences in individual phase estimates are real or due to methodological     
differences.  That is, differences may be due to changes in sampling methods    
or data collection methodology over time.  At this time, there is no valid      
statistical test for examining differences between Phase 1 and Phase 2.         
Therefore, although point estimates can be produced separately for each         
phase, no test is available to test whether those estimates are                 
significantly different from each other.                                        
                                                                                
NHANES III is based on a complex, multi-stage probability sample design.        
Several aspects of the NHANES design must be taken into account in data         
analysis, including the sample weights and the complex survey design.           
Appropriate sample weights are needed to estimate prevalence, means,            
medians, and other statistics.  Sample weights are used to produce correct      
population estimates because each sample person does not have the same          
probability of selection.  The sample weights incorporate the differential      
probabilities of selection and include adjustments for noncoverage and          
nonresponse.  A detailed discussion of nonresponse adjustments and issues       
related to survey coverage have been published (U.S. DHHS, 1996).  With the     
large oversampling of young children, older persons, black persons, and         
Mexican-Americans in NHANES III, it is essential that the sample weights be     
used in all analyses.  Otherwise, a misinterpretation of results is highly      
likely.  Other aspects of the design that must be taken into account in data    
analyses are the strata and PSU pairings from the sample design.  These         
pairings should be used to estimate variances and test for statistical          
significance.  For weighted analyses, analysts can use special computer         
software packages that use an appropriate method for estimating variances for   
complex samples such as SUDAAN (Shah, 1995) and WesVarPC (Westat, 1996).        
                                                                                
Although initial exploratory analyses may be performed on unweighted data       
using standard statistical packages and assuming simple random sampling,        
final analyses should be done on weighted data using appropriate sample         
weights.  A summary of the weighting methodology and the type of sample         
weights developed for NHANES III is included in Weighting and Estimation        
Methodology (U.S. DHHS, 1996).                                                  
                                                                                
The purpose of weighting the sample data is to permit analysts to produce       
estimates of statistics that would have been obtained if the entire             
sampling frame (the United States) had been surveyed.  Sample weights can be    
considered as measures of the number of persons the particular sample           
observation represents.  Weighting takes into account several features of       
the survey:  the specific probabilities of selection for the individual         
domains that were oversampled as well as nonresponse and differences between    
the sample and the total U.S. population.  Differences between the sample and   
                                                                                
                                                                               
the population may arise due to sampling variability, differential              
undercoverage in the survey among demographic groups, and possibly other        
types of response errors, such as differential response rates or                
misclassification errors.  Sample weighting in NHANES III was used to:          
                                                                                
1.   Compensate for differential probabilities of selection among subgroups     
     (i.e., age-sex-race-ethnicity subdomains where persons living in           
     different geographic strata were sampled at different rates);              
2.   Reduce biases arising from the fact that nonrespondents may be             
     different from those who participate;                                      
3.   Bring sample data up to the dimensions of the target population            
     totals;                                                                    
4.   Compensate, to the extent possible, for inadequacies in the sampling       
     frame (resulting from omissions of some housing units in the listing       
     of area segments, omissions of persons with no fixed address, etc.); and   
5.   To reduce variances in the estimation procedure by using auxiliary         
     information that is known with a high degree of accuracy.                  
                                                                                
In NHANES III, the sample weighting was carried out in three stages.  The       
first stage involved the computation of weights to compensate for unequal       
probabilities of selection (objective 1, above).  The second stage adjusted     
for nonresponse (objective 2).  The third stage used poststratification of      
the sample weights to Census Bureau estimates of the U.S. population to         
accomplish the third, fourth, and fifth objectives simultaneously.  In          
NHANES III, several types of sample weights (see the sample weights table       
that follows) were computed for the interviewed and examined sample and are     
included in the NHANES III data file.  Also, sample weights were computed       
separately for Phase 1 (1988-91), Phase 2 (1991-94), and total NHANES III       
(1988-94) to facilitate analysis of items collected only in Phase 1, only       
in Phase 2, and over six years of the survey.  Three sets of pseudo strata      
and PSU pairings are provided to use with SUDAAN in variance estimation.        
Since NHANES III is based on a complex, multi-stage sample design,              
appropriate sample weights should be used in analyses to produce national       
estimates of prevalence and associated variances while accounting for           
unequal probability of selection of sample persons.  For example, the final     
interview weight, WTPFQX6, should be used for analysis of the items or          
questions from the family or household questionnaires, and the final MEC        
examination weight, WTPFEX6, should be used for analysis of the                 
questionnaires and measurements administered in the MEC.  Furthermore, for a    
combined analysis of measurements from the MEC examinations and associated      
medical history questions from the household interview, the final MEC           
examination weight, WTPFEX6, should be used.  We recommend using SUDAAN         
(Shah, 1995) to estimate statistics of interest and the associated variance.    
However, one can also use other published methods for variance estimation.      
Application of SUDAAN and alternative methods, such as the average design       
effect approach, balance repeated replication (BRR) methods, or jackknife       
methods for variance estimation, are discussed in Weighting and Estimation      
Methodology (U.S. DHHS, 1996).                                                  
                                                                                
                                                                               
Appropriate Uses of the NHANES III Sample Weights                               
                                                                                
                                                                                
                                                                                
Final interview weight, WTPFQX6                                                 
                                                                                
          Use only in conjunction with the sample interviewed at home and       
          with items collected during the household interview.                  
                                                                                
                                                                                
Final examination (MEC only) weight, WTPFEX6                                    
                                                                                
          Use only in conjunction with the MEC-examined sample and with         
          interview and examination items collected at the MEC.                 
                                                                                
                                                                                
Final MEC+home examination weight, WTPFHX6                                      
                                                                                
          Use only in conjunction with the MEC+home-examined sample and         
          with items collected at both the MEC and home.                        
                                                                                
                                                                                
Final allergy weight, WTPFALG6                                                  
                                                                                
          Use only in conjunction with the allergy subsample and with items     
          collected as part of the allergy component of the exam.               
                                                                                
                                                                                
Final CNS weight, WTPFCNS6                                                      
                                                                                
          Use only in conjunction with the CNS subsample and with items         
          collected as part of the CNS component of the exam.                   
                                                                                
                                                                                
Final morning examination (MEC only) subsample weight, WTPFSD6                  
                                                                                
          Use only in conjunction with the MEC-examined persons assigned to     
          the morning subsample and only with items collected in the MEC        
          exam.                                                                 
                                                                                
                                                                                
Final afternoon/evening examination (MEC only) subsample weight, WTPFMD6        
                                                                                
          Use only in conjunction with the MEC-examined persons assigned to     
          the afternoon/evening subsample and only with items collected in      
          the MEC exam.                                                         
                                                                                
                                                                                
Final morning examination (MEC+home) subsample weight, WTPFHSD6                 
                                                                                
          Use only in conjunction with the MEC- and home-examined persons       
          assigned to the morning subsample and with items collected during     
          the MEC and home examinations.                                        
                                                                                
                                                                                
Final afternoon/evening examination (MEC+home) weight, WTPFHMD6                 
                                                                                
          Use only in conjunction with the MEC- and home-examined persons       
          assigned to the afternoon/evening subsample and with items            
          collected during the MEC and home examinations.                       
                                                                                
                                                                               
               DATA PREPARATION AND PROCESSING PROCEDURES                       
                                                                                
                                                                                
Automated data collection procedures for the survey were introduced in          
NHANES III.  In the mobile examination centers, data for the interview and      
examination components were recorded directly onto a computerized data          
collection form.  With the exception of a few independently automated           
systems, the system was centrally integrated.  This operation allowed for       
ongoing monitoring of much of the data.  Before the introduction of the         
computer-assisted personal interview (CAPI), the household questionnaire        
data were reviewed manually by field editors and interviewers.  CAPI            
(1992-1994 only) questionnaires featured built-in edits to prevent entering     
inconsistencies and out-of-range responses.  The multi-level data               
collection and quality control systems are discussed in detail in the Plan      
and Operation of the Third National Health and Nutrition Examination Survey,    
1988-1994 (NCHS, 1994; U.S. DHHS, 1996).  All interview, laboratory, and        
examination data were sent to NCHS for final processing.                        
                                                                                
Guidelines were developed that provided standards for naming variables,         
filling missing values and coding conventional responses, handling missing      
records, and standardizing two-part quantity/unit questionnaire variables.      
NCHS staff, assisted by contract staff, developed data editing                  
specifications that checked data sets for valid codes, ranges, and skip         
pattern consistencies and examined the consistency of values between            
interrelated variables.  Comments, collected in both interviews and             
examination components, were reviewed and recoded when possible.  Responses     
to "Other" and "Specify" were recoded either to existing code categories or     
to new categories.  The documentation for each data set includes notes for      
those variables that have been recoded and standardized and for those           
variables that differ significantly from what appears in the original data      
collection instrument.  While the data have undergone many quality control      
and editing procedures, there still may be values that appear extreme or        
illogical.  Values that varied considerably from what was expected were         
examined by analysts who checked for comments or other responses that might     
help to clarify unusual values.  Generally, values were retained unless they    
could not possibly be true, in which case they were changed to "Blank but       
applicable."  Therefore, the user must review each data set for extreme or      
inconsistent values and determine the status of each value for analysis.        
                                                                                
Several editing conventions were used in the creation of final analytic         
data sets:                                                                      
                                                                                
1.   Standardized variables were created to replace all two-part                
     quantity/unit questions using standard conversion factors.                 
     Standardized variables have the same name as the variable of the           
     two-part question with an "S" suffix.  For instance, MAPF18S (Months       
     received WIC benefits) in the MEC Adult Questionnaire was created from     
     the two-part response option to question F18, "How long did you receive    
     benefits from the WIC program?," using the conversion factor 12 months     
     per year.                                                                  
                                                                                
2.   Recoded variables were created by combining responses from two or more     
     like variables, or by collapsing responses to create a summary             
     variable for the purpose of confidentiality.  Recoded variables have the   
     original variable name with an R suffix.  For example, place of birth      
     variable (HFA6X) in the Family Questionnaire was collapsed to a three      
     level response category (U.S., Mexico, Other) and renamed HFA6XR.          
     Generally, only the recoded variable has been included in the data file.   
                                                                                
                                                                               
3.   Fill values, a series of one or more digits, were used to represent        
     certain specific conditions or responses.  Below is a list of the fill     
     values that were employed.  Some of the fill values pertain only to        
     questionnaire data, although 8-fill and blank-fill values are found in     
     all data sets.  Other fill values, not included in this list, are used     
     to represent component-specific conditions.                                
                                                                                
     6-fills = Varies/varied. (Questionnaires only)                             
                                                                                
     7-fills = Fewer than the smallest number that could be reported within     
     the question structure (e.g., fewer than one cigarette per day).           
     (Questionnaires only)                                                      
                                                                                
     8-fills = Blank but applicable/cannot be determined.  This means that      
     a respondent was eligible to receive the question, test, or component      
     but did not because of refusal, lack of time, lack of staff, loss of       
     data, broken vial, language barrier, unreliability, or other similar       
     reasons.                                                                   
                                                                                
     9-fills = Don't know.  This fill was used only when a respondent did       
     not know the response to a question and said, "I don't know."              
     (Questionnaires only)                                                      
                                                                                
     Blank fills = Inapplicable.  If a respondent was not eligible for a        
     questionnaire, test, or component because of age, gender, or specific      
     reason, the variable was blank-filled.  In the questionnaire, if a         
     respondent was not asked a question because of a skip-pattern,             
     variables corresponding to the question were blank-filled.  For            
     examination or laboratory components, if a person was excluded by a        
     defined protocol (e.g., screening exclusion questions) and these           
     criteria are included in the data set, then the corresponding              
     variables were blank-filled for that person.  For home examinees,          
     variables for examination components and blood tests not performed as      
     part of the home examination protocol were blank-filled.                   
                                                                                
4.   For variables describing discrete data, codes of zero (0) were used to     
     mean "none," "never," or the equivalent.  Value labels for which "0"       
     is used include:  "has not had," "never regularly," "still taking," or     
     "never stopped using."  Unless otherwise labeled, for variables            
     containing continuous data, "zero" means "zero.                            
                                                                                
5.   Where there are logical skip patterns in the flow of the questionnaire     
     or examination component, the skip was indicated by placing the            
     variable label of the skip destination in parentheses as part of the       
     value label of the response generating the skip.  For example, in the      
     Physical Function Evaluation, the variable PFPWC (in wheelchair) has a     
     value label, "2  No (PFPSCOOT)" that means that the next item for          
     persons not in a wheelchair would be represented by the variable,          
     PFPSCOOT.                                                                  
                                                                                
                                                                                
Variable Nomenclature                                                           
                                                                                
A unique name was assigned to every NHANES III variable using a standard        
convention.  By following this naming convention, the origin of each            
variable is clear, and there is no chance of overlaying similar variables       
across multiple components.  Variables range in length from three to eight      
characters.  The first two variable characters represent the topic (e.g.,       
analyte, questionnaire instrument, examination component) and are listed        
below alphabetically by topic.  For questionnaires administered in the          
household, the remainder of the variable name following the first two           
                                                                               
characters indicates the question section and number.  For example, data        
for the response to the Household Adult Questionnaire question B1 are           
contained in the variable HAB1.  For most laboratory and examination            
variables, as well as some other variables, a "P" in the third position         
refers to "primary" and the remainder of the variable name is a brief           
description of the item.  For instance, in the Laboratory Data File,            
information on the length of time the person fasted before the first blood      
draw is contained in the variable PHPFAST.  The variable PHPFAST was derived    
as follows:  characters 1-2 (PH) refer to "phlebotomy," character 3 (P)         
refers to "primary," characters 4-8 (FAST) refer to an abbreviation for         
"fasting."                                                                      
                                                                                
                                                                                
CODE           TOPIC                                                            
                                                                                
AT             Alanine aminotransferase (from biochemistry profile)             
AM             Albumin (from biochemistry profile)                              
AP             Alkaline phosphatase (from biochemistry profile)                 
AL             Allergy skin test                                                
AC             Alpha carotene                                                   
AN             Anisocytosis                                                     
AA             Apolipoprotein (AI)                                              
AB             Apolipoprotein (B)                                               
AS             Aspartate aminotransferase (from biochemistry profile)           
LA             Atypical lymphocyte                                              
AU             Audiometry                                                       
BA             Band                                                             
BO             Basophil                                                         
BS             Basophilic stippling                                             
BC             Beta carotene                                                    
BX             Beta cryptoxanthin                                               
BL             Blast                                                            
BU             Blood urea nitrogen (BUN) (from biochemistry profile)            
BM             Body measurements                                                
BD             Bone densitometry                                                
C1             C-peptide (first venipuncture)                                   
C2             C-peptide (second venipuncture)                                  
CR             C-reactive protein                                               
UD             Cadmium                                                          
CN             Central nervous system function evaluation                       
CL             Chloride (from biochemistry profile)                             
CO             Cotinine                                                         
CE             Creatinine (serum)(from biochemistry profile)                    
UR             Creatinine (urine)                                               
DM             Demographic                                                      
DE             Dental examination                                               
MQ             Diagnostic interview schedule                                    
DR             Dietary recall (total nutrient intakes)                          
EO             Eosinophil                                                       
EP             Erythrocyte protoporphyrin                                       
FR             Ferritin                                                         
FB             Fibrinogen                                                       
RB             Folate (RBC)                                                     
FO             Folate (serum)                                                   
FH             Follicle stimulating hormone (FSH)                               
FP             Fundus photography                                               
                                                                                
                                                                               
CODE           TOPIC                                                            
                                                                                
GG             Gamma glutamyl transferase (GGT) (from biochemistry profile)     
GU             Gallbladder ultrasonography                                      
GB             Globulin (from biochemistry profile)                             
G1             Glucose (first venipuncture)                                     
G2             Glucose (second venipuncture)                                    
SG             Glucose (from biochemistry profile)                              
GH             Glycated hemoglobin                                              
GR             Granulocyte                                                      
C3             HCO3 (Bicarbonate)(from biochemistry profile)                    
HD             HDL cholesterol                                                  
HP             Helicobacter pylori antibody                                     
HT             Hematocrit                                                       
HG             Hemoglobin                                                       
AH             Hepatitis A antibody (HAV)                                       
HB             Hepatitis B core antibody (anti-HBc)                             
SS             Hepatitis B surface antibody (anti-HBs)                          
SA             Hepatitis B surface antigen (HBsAg)                              
HC             Hepatitis C antibody (HCV)                                       
DH             Hepatitis D antibody (HDV)                                       
H1             Herpes 1 antibody                                                
H2             Herpes 2 antibody                                                
HX             Home examination (general)                                       
HF             Household family questionnaire                                   
HA             Household adult questionnaire                                    
HQ             Household questionnaire variables (composite)                    
HS             Household screener questionnaire                                 
HY             Household youth questionnaire                                    
HZ             Hypochromia                                                      
I1             Insulin (first venipuncture)                                     
I2             Insulin (second venipuncture)                                    
UI             Iodine (urine)                                                   
FE             Iron                                                             
SF             Iron (from biochemistry profile)                                 
LD             Lactate dehydrogenase (from biochemistry profile)                
L1             Latex antibody                                                   
LC             LDL cholesterol (calculated)                                     
PB             Lead                                                             
LP             Lipoprotein (a)                                                  
LH             Luteinizing hormone                                              
LU             Lutein/zeaxanthin                                                
LY             Lycopene                                                         
LM             Lymphocyte                                                       
MR             Macrocyte                                                        
MC             Mean cell hemoglobin (MCH)                                       
MH             Mean cell hemoglobin concentration (MCHC)                        
MV             Mean cell volume (MCV)                                           
PV             Mean platelet volume                                             
MA             MEC adult questionnaire                                          
MX             MEC examination (general)                                        
FF             Dietary food frequency (ages 12-16 years)                        
MP             MEC proxy questionnaire                                          
MY             MEC youth questionnaire                                          
ME             Metamyelocyte                                                    
MI             Microcyte                                                        
MO             Monocyte                                                         
MN             Mononuclear cell                                                 
ML             Myelocyte                                                        
                                                                                
                                                                               
CODE           TOPIC                                                            
                                                                                
IC             Normalized calcium (derived from ionized calcium)                
OS             Osmolality (from biochemistry profile)                           
PH             Phlebotomy data collected in MEC (e.g., questions)               
PS             Phosphorus (from biochemistry profile)                           
PF             Physical function evaluation                                     
PE             Physician's examination                                          
PL             Platelet                                                         
DW             Platelet distribution width                                      
PK             Poikilocytosis                                                   
PO             Polychromatophilia                                               
SK             Potassium (from biochemistry profile)                            
PR             Promyelocyte                                                     
RC             Red blood cell count (RBC)                                       
RW             Red cell distribution width (RDW)                                
RE             Retinyl esters                                                   
RF             Rheumatoid factor antibody                                       
RU             Rubella antibody                                                 
WT             Sample weights                                                   
SE             Selenium                                                         
SI             Sickle cell                                                      
NA             Sodium (from biochemistry profile)                               
SH             Spherocyte                                                       
SP             Spirometry                                                       
SD             Survey design                                                    
TT             Target cell                                                      
TE             Tetanus                                                          
TB             Total bilirubin (from biochemistry profile)                      
CA             Total calcium                                                    
SC             Total calcium (from biochemistry profile)                        
TC             Total cholesterol                                                
CH             Total cholesterol (from biochemistry profile)                    
TI             Total iron binding capacity (TIBC)                               
TP             Total protein (from biochemistry profile)                        
TX             Toxic granulation                                                
TO             Toxoplasmosis antibody                                           
PX             Transferrin saturation                                           
TG             Triglycerides                                                    
TR             Triglycerides (from biochemistry profile)                        
TY             Tympanometry                                                     
UA             Uric acid (from biochemistry profile)                            
UB             Urinary albumin                                                  
VU             Vacuolated cells                                                 
VR             Varicella antibody                                               
VA             Vitamin A                                                        
VB             Vitamin B12                                                      
VC             Vitamin C                                                        
VE             Vitamin E                                                        
WC             White blood cell count (WBC)                                     
WW             WISC/WRAT cognitive test                                         
                                                                                
                                                                               
                             GENERAL REFERENCES                                 
                                                                                
                                                                                
Delgado JL, Johnson CL, Roy I, Trevino FM.  Hispanic Health and Nutrition       
Examination Survey:  methodological considerations.  Amer J Pub Health          
80(suppl.):6-10.  1990.                                                         
                                                                                
Engel A, Murphy RS, Maurer K, Collins E.  Plan and operation of the HANES I     
Augmentation Survey of Adults 25-74 Years, United States, 1974-75.              
National Center for Health Statistics.  Vital Health Stat 1(14).  1978.         
                                                                                
Freeman DH, Freeman JL, Brock DB, Koch GG.  Strategies in the multivariate      
analysis of data from complex surveys II:  an application to the United         
States National Health Interview Survey.  Int Stat Rev 40(3):317-30.  1976.     
                                                                                
Khare M, Mohadjer LK, Ezzati-Rice TM, Waksberg J.  An evaluation of             
nonresponse bias in NHANES III (1988-91).  1994 Proceedings of the Survey       
Research Methods section of the American Statistical Association.  1994.        
                                                                                
Landis JR, Lepkowski JM, Eklund SA, Stehouwer SA.  A statistical                
methodology for analyzing data from a complex survey, the first National        
Health and Nutrition Examination Survey.  National Center for Health            
Statistics.  Vital Health Stat 2(92).  1982.                                    
                                                                                
McDowell A, Engel A, Massey JT, Maurer K.  Plan and operation of the second     
National Health and Nutrition Examination Survey, 1976-80.  National Center     
for Health Statistics.  Vital Health Stat 1(15).  1981.                         
                                                                                
Miller HW.  Plan and operation of the Health and Nutrition Examination          
Survey, United States, 1971-1973.  National Center for Health Statistics.       
Vital Health Stat 1(10a) and (10b).  1973.                                      
                                                                                
National Center for Health Statistics.  Plan and initial program of the         
Health Examination Survey.  Vital Health Stat 1(4).  1965.                      
                                                                                
National Center for Health Statistics.  Plan and operation of a health          
examination survey of U.S. youths 12-17 years of age.  Vital Health Stat        
1(8).  1969.                                                                    
                                                                                
National Center for Health Statistics.  Plan and operation of the Hispanic      
Health and Nutrition Examination Survey, 1982-84.  Vital Health Stat 1(19).     
1985.                                                                           
                                                                                
National Center for Health Statistics.  Plan and operation of the Third         
National Health and Nutrition Examination Survey, 1988-94.  Vital Health        
Stat 1(32).  1994.                                                              
                                                                                
National Center for Health Statistics.  Plan, operation, and response           
results of a program of children's examinations.  Vital Health Stat 1(5).       
1967.                                                                           
                                                                                
Shah BV, Barnwell BG, Bieler GS.  SUDAAN User's Manual: Software for            
Analysis of Correlated Data.  Research Triangle Park, NC:  Research Triangle    
Institute.  Release 6.04.  1995.                                                
                                                                                
Skinner CJ.  Aggregated analysis:  standard errors and significance tests.      
In:  Skinner CJ, Holt D, Smith TMF, eds.  Analysis of complex surveys.  New     
York:  John Wiley and Sons, Inc.  1989.                                         
                                                                                
                                                                               
U.S. Department of Health and Human Services (DHHS).  National Center for       
Health Statistics.  NHANES III reference manuals and reports (CD-ROM).          
Hyattsville, MD:  Centers for Disease Control and Prevention, 1996.             
Available from National Technical Information Service (NTIS), Springfield,      
VA.  Acrobat .PDF format; includes access software:  Adobe Systems, Inc.        
Acrobat Reader 2.1.                                                             
                                                                                
Westat, Inc.  A User's Guide to WesVarPC.  Rockville, MD.  Westat, Inc.         
1996.                                                                           
                                                                                
Yetley E, Johnson C.  Nutritional applications of the Health and Nutrition      
Examination Surveys (HANES).  Annu Rev Nutr 7:441-63. 1987.                     
                                                                                
                                                                               
NHANES III Dietary Interview Component                                          
                                                                                
Dietary interviews were administered to all examinees by a trained dietary      
interviewer in the mobile examination center (MEC).  Respondents reported all   
foods and beverages consumed except plain drinking water (i.e., not bottled) for
the previous 24-hour time period (midnight to midnight).  An automated,         
microcomputer-based dietary interview and coding system known as the NHANES III 
Dietary Data Collection (DDC) System was used to collect all NHANES III dietary 
recall data.  The DDC system was developed for use in the survey by the         
University of Minnesota's Nutrition Coordinating Center (NCC).                  
                                                                                
The dietary interviews were conducted in English and Spanish by                 
bilingual dietary interviewers in a private room to ensure                      
confidentiality.  Proxy respondents were permitted for infants and children aged
two months through five years and for other respondents who were unable to      
report on their own.  Children aged six to 11 years were permitted to report    
their own intake if the interviewer deemed it acceptable and appropriate, but   
many interviewers for respondents in this age category were completed by proxy  
or with the child and a proxy.  The dietary interviewers contacted other        
information sources such as care providers and schools to obtain complete       
dietary intake data for respondents.                                            
                                                                                
The primary source of food composition data for NHANES III is the U.S.          
Department of Agriculture (USDA) Survey Nutrient Database; two nutrient files   
were provided by USDA for use in NHANES III (USDA 1993, 1995). Each USDA file   
contained food composition values that were appropriate for the time period     
during which the NHANES III data were collected. Additionally, food composition 
data for a small number of herbs and spices were obtained from NCC (NCC, 1996). 
                                                                                
The DDC system's foods database was designed specifically to handle time-related
changes in food descriptions, food amounts, and recipes; updated information was
applied retrospectively to data collected in the early part of NHANES III.  As  
was mentioned earlier, two USDA food composition databases were used to assign  
nutrient values to the NHANES III dietary recalls (USDA 1993; USDA, 1995).  In  
addition to data changes that occurred in the nutrient values of foods due to   
food product reformulations, recipe changes, and so forth, the U.S. marketplace 
underwent tremendous growth and change as new food product lines were introduced
and new food components were added to the food                                  
supply (e.g., fat substitutes and artificial sweeteners).  The impact of these  
and other changes may require additional analysis.                              
                                                                                
Dietary recall interviews were edited by the interviewers to ensure that they   
were as complete as possible.  NCHS completed all final editing and             
determinations regarding the completeness and reliability of the dietary        
recalls.  Analysts should note that the data reported are self-reported data.   
Extreme values were verified.                                                   
                                                                                
Information pertaining to the use of nutritional supplements and                
antacids was reported separately during the Household Adult and                 
Household Youth Interviews.                                                     
                                                                                
                                                                               
A number of quality-control monitoring techniques were employed during the      
survey.  The techniques for monitoring the Dietary Interview component included 
observations of actual dietary interviews and reviews of audiotape interviews by
NCHS and contractor staff. In addition, the dietary interviewers worked in      
two-person teams; there was one team in each MEC.  The dietary interviewers     
performed 10-percent cross-check reviews of their partners' work using printed  
recall reports.  Finally, newsletters, field memoranda, telephone calls, and    
staff retraining sessions were other methods used to maintain quality control   
during the survey.  Refer to the NHANES III Dietary Interviewer's Training      
Manual for the dietary interview protocol (U.S. DHHS, 1996b).                   
                                                                                
Analysts are encouraged to use six years of survey data in their                
analyses.  The reliability of estimates is improved when larger sample sizes are
used.  For more detailed information, see the Analytic and Reporting Guidelines 
for NHANES III (U.S. DHHS, 1996b).  In addition, MEC final examination weights  
(WTPFEX6) should be used when analyzing the total nutrient intake data and      
related questionnaire data in this file.  For more information on the use of    
sample weights in NHANES III data analysis, refer to the NHANES III Analytic and
Reporting Guidelines (U.S. DHHS, 1996b).                                        
                                                                                
                                                                               
NHANES III Total Nutrient Intakes and Foods Data Files                          
                                                                                
NCHS prepared 4 datasets that are based on the 24-hr dietary recall interview.  
Total nutrient intakes were reported in the NHANES III Examination Data file    
(Catalog 76200).  Three foods files were prepared; three files are found in     
Catalog 76700: NHANES III Individual Foods Data File from the Dietary Recall;   
NHANES III Combination Foods Data File from the Dietary Recall; NHANES III      
(Variable) Ingredients Data File from the Dietary Recall.  Documentation was    
prepared for each of the foods data files. Data users are encouraged to review  
all of the documentation prior to using the data files.                         
                                                                                
                                                                                
Look-up Tables for the NHANES III Foods Data Files                              
                                                                                
Textual descriptions for several NHANES III Foods Data File numeric code        
variables are located in an Appendix section that accompanies the Foods Data    
Files.  The Appendix files are referred to as "look-up" tables throughout the   
data file documentation for the Foods Data Files.  Computer code is provided so 
that data users can merge the foods data files with the information in the      
Appendix/look-up tables.                                                        
                                                                                
                                                                               
Variable Ingredients File                                                       
                                                                                
Ingredient Information                                                          
                                                                                
The approach used to classify elemental foods and recipe foods was described in 
the NHANES III Individuals Foods File documentation.  The Individual Foods File 
provides information about the component foods that were reported during the    
dietary interview.  Many component foods were recipe foods.  Recipe foods have  
ingredient records, some of which were variable ingredients.  Variable          
ingredients were ingredients that the respondent could specify during the       
interview.  Many types of ingredients were variable; the DDC System targeted    
sources of fat and sodium in food.  Information about variable ingredients is   
reported in the NHANES III Variable Ingredients File (VIF).                     
                                                                                
An important concept to understand when using the NHANES III foods files is that
many foods can be component foods as well as  ingredients of component foods,   
depending on their use.  For example, margarine is included in the Individual   
Foods File as a component food.  Two examples of margarine as a component food  
were margarine spread on bread and margarine added to mashed potatoes at the    
table; in both examples, margarine is a component food and has a food gram      
weight, USDA food code, possibly a brand name, nutrients, and so forth.  The    
SAME margarine product may also be used as an ingredient in a recipe food such  
as homemade cookies.  If a respondent reported eating homemade cookies, a probe 
as to the type of fat used in the recipe was asked during the interview.  The   
Individual Foods File record for this food would report the type of cookie, the 
amount eaten, and nutrients for the cookie.  The Variable Ingredients File (VIF)
reports information about the margarine ingredient that was used to prepare the 
cookies; the VIF record includes a USDA food code for the margarine and possibly
a brand name.                                                                   
                                                                                
The VIF reports information pertaining to the variable ingredients for many     
recipe foods in the Individual Foods File.  Only ingredients that the survey    
respondents were asked to specify are included in the VIF; other recipe         
ingredients that were not presented to respondents are excluded from the VIF.   
For example, if a respondent reported eating tuna salad, the variable ingredient
probes included a probe as to the type of tuna fish, a probe as to whether the  
tuna was rinsed or drained, and a probe as to the type of mayonnaise or salad   
dressing used.  The VIF provides information about these variable ingredients.  
On the other hand, the tuna salad may also have celery, pickles, and onion      
ingredients, but these ingredients were not variable ingredients.  Again, the   
DDC System variable ingredient probes targeted sources of fat and sodium in the 
diet.                                                                           
                                                                                
                                                                               
Notes to Data Users:                                                            
                                                                                
1.   Atypical Recipes and Modified Recipes                                      
                                                                                
If a respondent reported that a food was prepared using what might be considered
to be atypical or unusual ingredients, the dietary interviewers noted this.  For
example, some respondents used yogurt instead of mayonnaise to prepare salads.  
Additionally, respondents added unusual components to foods.  The interviewers  
were instructed to note information about the ingredients that were used to     
prepare foods.   NCHS evaluated the interviewers' notes and finalized the       
entries for all foods reported during the survey.                               
                                                                                
Respondents also modified recipes by omitting fat, substituting lower fat       
ingredients, using egg substitute products instead of whole eggs, etc.  The     
recipe information that was recorded during the dietary interview was used to   
modify a standard recipe or locate another suitable recipe so that the food     
could be entered into the DDC System as a multi-component/combination food.     
Modified recipe food components included ingredient-type items such as flour and
salt.  The Individual Foods File reports the component level information.  The  
multi-component foods have descriptive data in the Combination Foods File.      
                                                                                
2.   Default Ingredients in the VIF                                             
                                                                                
Respondent-specified variable ingredients are reported in the VIF.  If the      
respondent did not know anything about the ingredients that were used to prepare
a food, the DDC System assigned a default ingredient automatically.  There are  
default ingredients for home-prepared and commercially-prepared foods.  For     
example, if a respondent reported eating brownies that were purchased at a      
bakery, and the fat ingredient information was unknown, the DDC System default  
for commercial brownies, purchased at a bakery would be assigned to the food.   
Similarly, ingredients that were used to prepare home-prepared foods also had   
default ingredient options.  If a respondent ate a homemade meatloaf and could  
not specify the type of meat used, the DDC System assigned a default ingredient 
to the ingredient probes for the food.  The variable ingredient default code    
(DRPVIDC) denotes when default variable ingredients were assigned to foods; the 
DRPVIDC codes have a descriptive text with them.  For example, the type of fat  
used to fry a commercial food might be unknown so the DRPVIDC description might 
read: "fat used in frying unknown-commercially prepared".                       
                                                                                
3.   No Ingredients Added                                                       
                                                                                
If the respondent stated that variable ingredients were not used to prepare a   
particular food, the VIF will include an ingredient record for the omitted      
ingredient(s), but the ingredient food code (DRPICODE) field is blank for each  
omitted ingredient.  The ingredient identification code (DRPINGID) links to a   
look-up table called IDCODE that provides text descriptions for the omitted     
ingredients.  For example, cooked vegetables have fat and salt ingredient       
probes.  If the respondent stated that no fat or salt was added in preparation, 
the VIF ingredient identification code (DRPINGID) descriptions for each variable
ingredient will link to text information stating that no fat or salt was added  
in preparation.                                                                 
                                                                                
Note: The same look-up table called "IDCODE" is used for Food Identification    
Code (DRPFID) and Ingredient Identification Code (DRPINGID) text descriptions.  
DRPFID provides component level information as described in the Individual Foods
File documentation; DRPINGID provides ingredient level information found in the 
VIF.                                                                            
                                                                                
                                                                               
Summary                                                                         
                                                                                
The VIF provides information about respondent-specified variable ingredients,   
including default variable ingredients.  The VIF variables are sorted by case,  
meal number (DRPMN), food number (DRPFN), component number (DRPCN) and          
ingredient number (DRPIN). All variable ingredients that were added to a recipe 
food have a food code (DRPICODE); ingredient food codes link to food code       
descriptions in the look-up table "Codebook".  If a variable ingredient was     
reported by brand name, this information was included in the VIF; the brand name
code (DRPCOMM) is linked to a brand name description in a look-up table called  
"BRANDS".  The ingredient identification code (DRPINGID) for all variable       
ingredients provides descriptive information about variable ingredients;        
DRPINGID is linked to the look-up table "IDCODE".                               
                                                                                
                                                                               
              NHANES III Variable Ingredient Foods Data File Index              
                            from the Dietary Recall                             
                                                                                
    ------------------------------------------------------------------------    
                                                   Variable                     
    Description                                    Name         Positions       
    ------------------------------------------------------------------------    
                                                                                
    VARIABLE INGREDIENTS FILE                                                   
                                                                                
    Respondent identification number ............  SEQN                 1-5     
    Meal Number .................................  DRPMN                6-7     
    Food Number .................................  DRPFN                8-9     
    Component Number ............................  DRPCN              10-11     
    Ingredient Number ...........................  DRPIN              12-13     
    Parent. USDA Food Code ......................  DRPFCODE           14-20     
    USDA Ingredient Food Code ...................  DRPICODE           21-27     
    Ingredient ID. Table look-up description ....  DRPINGID           28-31     
    Brand Id/Commercial Code ....................  DRPCOMM            32-35     
    Variable ingredient Default Code ............  DRPVIDC            36-38     
                                                                                
                                                                               
                 NHANES III Variable Ingredient Foods Data File                 
                            from the Dietary Recall                             
                                                                                
    ------------------------------------------------------------------------    
    FILENAME=VIF                 VERSION 1.0                        N=126070    
    ------------------------------------------------------------------------    
                           VARIABLE INGREDIENTS FILE                            
    ------------------------------------------------------------------------    
    Positions            Item description                                       
    SAS name    Counts       and code                               Notes       
    ------------------------------------------------------------------------    
                                                                                
           1-5             Sample person identification number                  
      SEQN        126070   00003-53621                                          
                                                                                
           6-7             Meal number                              See note    
      DRPMN       126070   01-16                                                
                                                                                
           8-9             Food number                              See note    
      DRPFN       126070   01-29                                                
                                                                                
          10-11            Component number                         See note    
      DRPCN       126070   01-13                                                
                                                                                
          12-13            Ingredient number                        See note    
      DRPIN       126070   01-36                                                
                                                                                
          14-20            Component food code                      See note    
      DRPFCODE    126070   1151200-9330140                                      
                                                                                
          21-27            Ingredient food code                     See note    
      DRPICODE     96566   0004055-9241051                                      
                   29504   Blank                                                
                                                                                
          28-31            Ingredient ID code                       See note    
      DRPINGID    111679   0274-7285                                            
                   14391   Blank                                                
                                                                                
          32-35            Brand or commercial ID code              See note    
      DRPCOMM      14391   0108-6775                                            
                  111679   Blank                                                
                                                                                
                                                                               
                                                                                
                 NHANES III Variable Ingredient Foods Data File                 
                            from the Dietary Recall                             
                                                                                
    ------------------------------------------------------------------------    
                           VARIABLE INGREDIENTS FILE                            
    ------------------------------------------------------------------------    
    Positions            Item description                                       
    SAS name    Counts       and code                               Notes       
    ------------------------------------------------------------------------    
                                                                                
          36-38            Variable ingredient default code         See note    
      DRPVIDC         24   BKY   Unknown-prepared in bakery                     
                    8624   C     Unknown-commercially prepared                  
                    1842   H     Unknown-prepared at home                       
                     374   MIX   Unknown-prepared from commercial               
                                 mix                                            
                      45   RCP   Unknown-prepared from recipe                   
                       4   RST   Unknown-prepared in restaurant                 
                    2832   UF    Unknown if fat used                            
                    6829   UK    Unknown                                        
                       6   UMH   Unknown if prepared from mix or                
                                 at home                                        
                       6   UMR   Unknown if prepared from mix or                
                                 a recipe                                       
                    6360   US    Unknown if salt added in                       
                                 preparation                                    
                    4738   UTF   Unknown type of fat used                       
                   94386   Blank                                                
                                                                                
                                                                               
Notes                                                                           
                                                                                
                                                                                
DRPMN     Meal number                                                           
                                                                                
          Meal numbers in recalls that were complete and reliable (DRPSTAT=1)   
          always begin with meal number=1; meal numbers increase by one for each
          consecutive meal or snack reported during the dietary interview.  If a
          recall was coded reliable, but incomplete, (DRPSTAT=2) the meal       
          numbers may not be consecutive; information is reported for meals that
          were reported during the dietary interview.  Meal numbers are not     
          sorted by the time of day.                                            
                                                                                
DRPFN     Food number                                                           
                                                                                
          Every food has a food number.  Foods are numbered within meals.  If   
          the recall was coded complete and reliable (DRPSTAT=1), the first food
          in each meal has a food number=1, and the other foods reported in the 
          same meal are numbered consecutively.  If the recall was coded        
          reliable, but incomplete, (DRPSTAT=2) the food numbers may not be     
          consecutive; information is reported for all foods that were reported 
          by the respondent.                                                    
                                                                                
DRPCN     Component number                                                      
                                                                                
          Foods are comprised of one or more components.  An example of a single
          component food is a slice of bread.  A sandwich is an example of a    
          multiple component food or combination food; in this example, the     
          component foods consist of bread and sandwich filling components.     
          If a recall was coded reliable and complete (DRPSTAT=1), all          
          components are numbered consecutively within a given food; the        
          component numbering sequence for the first food begins with component 
          number=1 and increases by one for each additional component in the    
          food.  The numbering sequence is repeated for each additional food    
          reported.  If the recall was coded reliable, but                      
          incomplete,(DRPSTAT=2) the component numbers may not be consecutive;  
          information is reported for the components that were reported by the  
          respondent.                                                           
                                                                                
DRPIN     Ingredient number                                                     
                                                                                
          Component foods may have ingredient records associated with them.  The
          first ingredient of a component has ingredient number =1; ingredient  
          numbers increase by one for each additional ingredient of the         
          component food.  Variable ingredients are reported in the Variable    
          Ingredients File.                                                     
                                                                                
                                                                               
                                                                                
DRPICODE  Ingredient food code                                                  
                                                                                
          An ingredient food code was assigned to all ingredients that were used
          to prepare recipe foods.  Most of the ingredient food codes were USDA 
          Survey Nutrient Data Base food codes; NCC food codes were used to code
          some ingredients.  NCC nutrient values were used for the ingredients  
          that were assigned NCC food codes.  Text descriptions for the         
          ingredient food codes are listed in a look-up table called "Codebook".
                                                                                
                                                                                
                                                                                
     Blank     Blank values in the DRPICODE field denote that one or more       
               variable ingredients were omitted during food preparation.  The  
               ingredient food identification code (DRPINGID) provides a unique 
               food identification code for variable ingredients that were      
               omitted during food preparation; text descriptions for DRPINGID  
               are found in the look-up table called "IDCODE".                  
                                                                                
DRPINGID  Ingredient ID code                                                    
                                                                                
          A unique 4-digit code that provides additional descriptive information
          about the ingredients that were used to prepare recipe foods.   All   
          ingredient ID codes have a corresponding text description found in the
          look-up table called "IDCODE".                                        
                                                                                
DRPCOMM   Brand ID or fast food code                                            
                                                                                
          All brand name and fast food restaurant items reported during NHANES  
          III were assigned a 5-digit DRPCOMM.  DRPCOMM codes are linked to a   
          table of commercial foods text descriptions in the look-up table      
          called "Brands".                                                      
                                                                                
DRPVIDC   Variable ingredient default code                                      
                                                                                
          The DDC System assigned variable ingredients to foods automatically   
          when the respondent was unable to specify the ingredients that were   
          used to prepare recipe foods.  Each DRPVIDC has a text description    
          associated with it in the data file documentation.                    
                                                                                
                                                                               
SAS CODE TO MERGE LOOK-UP TABLES WITH VIF DATA FILE                             
                                                                                
*****--------------------------------------------*****;                         
*    1.0 Set library names.                          *;                         
*****--------------------------------------------*****;                         
                                                                                
libname in1 'VIF';                                                              
libname in2 'CODEBOOK';                                                         
libname in3 'BRANDS';                                                           
libname in4 'IDCODE';                                                           
                                                                                
*****--------------------------------------------*****;                         
*    2.1 Add USDA Food Descriptions                  *;                         
*****--------------------------------------------*****;                         
                                                                                
PROC SORT  DATA=IN1.VIF OUT=VIFDATA;                                            
           BY DRPICODE;                                                         
                                                                                
                                                                                
PROC SORT DATA=IN2.CODEBOOK OUT=CODEBOOK;                                       
           BY DRPFCODE;                                                         
                                                                                
DATA VIFDATA;                                                                   
           MERGE   VIFDATA(in=a)                                                
                   CODEBOOK(in=b rename=(drpfcode=DRPICODE));                   
           BY DRPICODE; IF A;                                                   
                                                                                
*****--------------------------------------------*****;                         
*    2.2 Add  Brands and Fast Food names             *;                         
*****--------------------------------------------*****;                         
                                                                                
PROC SORT  DATA=VIFDATA;                                                        
           BY DRPCOMM;                                                          
                                                                                
                                                                                
PROC SORT  DATA=IN3.BRANDS OUT=BRANDS;                                          
           BY DRPCOMM;                                                          
                                                                                
DATA VIFDATA;                                                                   
           MERGE  VIFDATA(in=a)                                                 
                  BRANDS(in=b);                                                 
           BY DRPCOMM; IF A;                                                    
                                                                                
*****--------------------------------------------*****;                         
*    2.3 Add NCC Food Descriptions                  *;                          
*****--------------------------------------------*****;                         
                                                                                
PROC SORT  DATA=VIFDATA;                                                        
           BY DRPINGID;                                                         
                                                                                
                                                                                
PROC SORT  DATA=IN4.IDCODE OUT=IDCODE;                                          
           BY DRPFID;                                                           
                                                                                
DATA VIFDATA;                                                                   
           MERGE  VIFDATA(in=a)                                                 
                  IDCODE(in=b rename=(drpfid=drpingid));                        
           BY DRPINGID ; IF A;                                                  
                                                                                
RUN;