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Third National Health and Nutrition Examination Survey
(NHANES III), 1988-94
Catalog Number 77550
NHANES III HOUSEHOLD YOUTH DATA FILE DOCUMENTATION
Ages 2 Months through 16 years
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 Household Youth Data
General Information . . . . . . . . . . . . . . . . . . . . . . . .
Data File Index . . . . . . . . . . . . . . . . . . . . . . . . . .
Data File Item Descriptions, Codes, Counts, and Notes . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 Household Youth 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 HFA6XCR.
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 Household Youth Data File
GENERAL INFORMATION
The NHANES III Household Youth Questionnaire Data File contains all data
collected during the household interviews for children and youths 2 months to 16
years of age. Demographic data, survey design variables, and sampling weights
for this age group are also included. This first section provides a brief
background and information about the contents of the Household Youth
Questionnaire Data File. The second section is the Data File Index, a
listing of all of the variables with the standard names and their positions in
the data set. The third section contains the frequency counts and codes for
all of the variables, followed by notes and appendices. References are found
in the fourth section.
The data that comprise this file were obtained from three separate interviews
administered in the household: the Screener, the Family, and Household Youth
questionnaires. The Screener was a brief interview administered to all
households within selected sampling units to determine eligibility for
participation in the survey. Information obtained from the Screener
questionnaire was the basis for the demographic variables, and survey-related
variables. The purpose of the Family questionnaire was to obtain data on
educational levels, occupation, health insurance coverage, income, and food
security of family members, and to record characteristics of the house itself.
The Household Youth questionnaire was administered to a proxy respondent,
usually the child's parent or guardian. Questions on topics such as birth
experience, motor and social development, health services usage, dental care,
selected medical conditions, school attendance, language, and vitamin, mineral
and medicine usage were asked according to age subgroups. The Household
Youth questionnaire was completed for 13,944 children and youths ages 2 months -
16 years of age during the six years of NHANES III.
Interviews were conducted by field staff, in both English and Spanish. All
staff received intensive initial training, and formal retraining was conducted
throughout the survey to ensure that high skill levels were maintained. The
data collection system was automated in Phase 2, at which time interviews were
conducted using CAPI (computer-assisted personal interview). Details on survey
instruments and forms, training manuals and data collection procedures are
published elsewhere (U.S. DHHS, 1996).
Data processing and editing were performed for consistency of responses within
sections of the questionnaire sections. Identifiable information including
names, addresses, and social security numbers, as well as other administrative
items were excluded from the data file in order to ensure confidentiality. Notes
are provided both for standardized and recoded variables, and for variables
requiring additional explanation. Hand cards and other diagrams that were used
during interviews are located with copies of the survey instruments in the Plan
and Operation of the Third National Health and Nutrition Examination Survey
(U.S. DHHS, 1996). Users should note that because questions were modified,
reordered, added, or deleted, this documentation may not follow the
exact ordering of the questions on survey instruments.
Since NHANES III was based on a complex multistage design, appropriate sample
weights should be used in analyses to produce national estimates and associated
variances. The final interview weights WTPFQX6 should be used for analysis of
interview data alone. If interview data are combined with examination,
laboratory or dietary data, the total MEC weights (WTPFEX6) or MEC+home weights
(WTPFHX6) should be used.
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
HOUSEHOLD SCREENER QUESTIONNAIRE (HSQ)
GENERAL INFORMATION
Sequence number ............................. SEQN 1-5
GENERAL INFORMATION
Family sequence number ...................... DMPFSEQ 6-10
Examination/interview status ................ DMPSTAT 11
Race-ethnicity .............................. DMARETHN 12
Race ........................................ DMARACER 13
Ethnicity ................................... DMAETHNR 14
GENERAL INFORMATION
Sex ......................................... HSSEX 15
Date of screener: month ..................... HSDOIMO 16-17
Age at interview (screener) - qty ........... HSAGEIR 18-19
Age at interview (screener) - unit .......... HSAGEU 20
Age in months at interview (screener) ....... HSAITMOR 21-24
Family size (persons in family) ............. HSFSIZER 25-26
Household size (persons in dwelling) ........ HSHSIZER 27-28
GENERAL INFORMATION
County code ................................. DMPCNTYR 29-31
FIPS code for State ......................... DMPFIPSR 32-33
Rural/urban code based on USDA code ......... DMPMETRO 34
Census region, weighting(Texas in south) .... DMPCREGN 35
Poverty Income Ratio (unimputed income) ..... DMPPIR 36-41
SURVEY DESIGN DATA
GENERAL INFORMATION
Phase of NHANES III Survey .................. SDPPHASE 42
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Total NHANES III pseudo-PSU ................. SDPPSU6 43
Total NHANES III pseudo-stratum ............. SDPSTRA6 44-45
Pseudo-PSU for phase 1 ...................... SDPPSU1 46
Pseudo-stratum for phase 1 .................. SDPSTRA1 47-48
Pseudo-PSU for phase 2 ...................... SDPPSU2 49
Pseudo-stratum for phase 2 .................. SDPSTRA2 50-51
SAMPLING WEIGHTS
TOTAL NHANES III (1988-94)
Total interviewed sample final weight ....... WTPFQX6 52-59
Total MEC examined sample final weight ...... WTPFEX6 60-67
Total M+H examined sample final weight ...... WTPFHX6 68-75
Total allergy subsample final weight ........ WTPFALG6 76-83
Total CNS subsample final weight ............ WTPFCNS6 84
Total morning subsample final wgt ........... WTPFSD6 85-93
Total afternoon/eve subsample final wgt ..... WTPFMD6 94-102
Total M+H morning subsample final wgt ....... WTPFHSD6 103-111
Total M+H afternoon subsample final wgt ..... WTPFHMD6 112-120
NHANES III PHASE 1 (1988-91)
Phase 1 interviewed sample final wgt ........ WTPFQX1 121-129
Phase 1 MEC examined sample final wgt ....... WTPFEX1 130-138
Phase 1 M+H examined sample final wgt ....... WTPFHX1 139-147
Phase 1 allergy subsample final wgt ......... WTPFALG1 148-156
Phase 1 CNS subsample final wgt ............. WTPFCNS1 157
Phase 1 morning sess subsample final wgt .... WTPFSD1 158-166
Phase 1 aft/eve subsample final wgt ......... WTPFMD1 167-175
Phase 1 morning M+H subsample final wgt ..... WTPFHSD1 176-184
Phase 1 aft/eve M+H subsample final wgt ..... WTPFHMD1 185-193
NHANES III PHASE 2 (1991-94)
Phase 2 interviewed sample final wgt ........ WTPFQX2 194-202
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Phase 2 MEC examined sample final wgt ....... WTPFEX2 203-211
Phase 2 M+H examined sample final wgt ....... WTPFHX2 212-220
Phase 2 allergy subsample final wgt ......... WTPFALG2 221-229
Phase 2 CNS subsample final wgt ............. WTPFCNS2 230
Phase 2 morning sess subsample final wgt .... WTPFSD2 231-239
Phase 2 aft/eve subsample final wgt ......... WTPFMD2 240-248
Phase 2 morning M+H subsample final wgt ..... WTPFHSD2 249-257
Phase 2 aft/eve M+H subsample final wgt ..... WTPFHMD2 258-266
FAY'S BRR REPLICATE INTERVIEW WEIGHTS
TOTAL NHANES III (1988-94)
Replicate 1 final interview weight .......... WTPQRP1 267-274
Replicate 2 final interview weight .......... WTPQRP2 275-282
Replicate 3 final interview weight .......... WTPQRP3 283-291
Replicate 4 final interview weight .......... WTPQRP4 292-299
Replicate 5 final interview weight .......... WTPQRP5 300-308
Replicate 6 final interview weight .......... WTPQRP6 309-316
Replicate 7 final interview weight .......... WTPQRP7 317-325
Replicate 8 final interview weight .......... WTPQRP8 326-333
Replicate 9 final interview weight .......... WTPQRP9 334-342
Replicate 10 final interview weight ......... WTPQRP10 343-351
Replicate 11 final interview weight ......... WTPQRP11 352-360
Replicate 12 final interview weight ......... WTPQRP12 361-369
Replicate 13 final interview weight ......... WTPQRP13 370-378
Replicate 14 final interview weight ......... WTPQRP14 379-386
Replicate 15 final interview weight ......... WTPQRP15 387-394
Replicate 16 final interview weight ......... WTPQRP16 395-403
Replicate 17 final interview weight ......... WTPQRP17 404-411
Replicate 18 final interview weight ......... WTPQRP18 412-420
Replicate 19 final interview weight ......... WTPQRP19 421-428
Replicate 20 final interview weight ......... WTPQRP20 429-436
Replicate 21 final interview weight ......... WTPQRP21 437-445
Replicate 22 final interview weight ......... WTPQRP22 446-454
Replicate 23 final interview weight ......... WTPQRP23 455-462
Replicate 24 final interview weight ......... WTPQRP24 463-470
Replicate 25 final interview weight ......... WTPQRP25 471-478
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Replicate 26 final interview weight ......... WTPQRP26 479-486
Replicate 27 final interview weight ......... WTPQRP27 487-494
Replicate 28 final interview weight ......... WTPQRP28 495-503
Replicate 29 final interview weight ......... WTPQRP29 504-512
Replicate 30 final interview weight ......... WTPQRP30 513-521
Replicate 31 final interview weight ......... WTPQRP31 522-530
Replicate 32 final interview weight ......... WTPQRP32 531-538
Replicate 33 final interview weight ......... WTPQRP33 539-546
Replicate 34 final interview weight ......... WTPQRP34 547-554
Replicate 35 final interview weight ......... WTPQRP35 555-562
Replicate 36 final interview weight ......... WTPQRP36 563-571
Replicate 37 final interview weight ......... WTPQRP37 572-580
Replicate 38 final interview weight ......... WTPQRP38 581-589
Replicate 39 final interview weight ......... WTPQRP39 590-597
Replicate 40 final interview weight ......... WTPQRP40 598-605
Replicate 41 final interview weight ......... WTPQRP41 606-614
Replicate 42 final interview weight ......... WTPQRP42 615-623
Replicate 43 final interview weight ......... WTPQRP43 624-631
Replicate 44 final interview weight ......... WTPQRP44 632-639
Replicate 45 final interview weight ......... WTPQRP45 640-648
Replicate 46 final interview weight ......... WTPQRP46 649-656
Replicate 47 final interview weight ......... WTPQRP47 657-665
Replicate 48 final interview weight ......... WTPQRP48 666-674
Replicate 49 final interview weight ......... WTPQRP49 675-682
Replicate 50 final interview weight ......... WTPQRP50 683-691
Replicate 51 final interview weight ......... WTPQRP51 692-699
Replicate 52 final interview weight ......... WTPQRP52 700-707
FAY'S BRR REPLICATE MEC EXAMINATION WEIGHTS
TOTAL NHANES III (1988-94)
Replicate 1 final exam weight ............... WTPXRP1 708-715
Replicate 2 final exam weight ............... WTPXRP2 716-724
Replicate 3 final exam weight ............... WTPXRP3 725-733
Replicate 4 final exam weight ............... WTPXRP4 734-742
Replicate 5 final exam weight ............... WTPXRP5 743-750
Replicate 6 final exam weight ............... WTPXRP6 751-758
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Replicate 7 final exam weight ............... WTPXRP7 759-767
Replicate 8 final exam weight ............... WTPXRP8 768-775
Replicate 9 final exam weight ............... WTPXRP9 776-784
Replicate 10 final exam weight .............. WTPXRP10 785-793
Replicate 11 final exam weight .............. WTPXRP11 794-802
Replicate 12 final exam weight .............. WTPXRP12 803-811
Replicate 13 final exam weight .............. WTPXRP13 812-820
Replicate 14 final exam weight .............. WTPXRP14 821-828
Replicate 15 final exam weight .............. WTPXRP15 829-836
Replicate 16 final exam weight .............. WTPXRP16 837-845
Replicate 17 final exam weight .............. WTPXRP17 846-853
Replicate 18 final exam weight .............. WTPXRP18 854-862
Replicate 19 final exam weight .............. WTPXRP19 863-870
Replicate 20 final exam weight .............. WTPXRP20 871-878
Replicate 21 final exam weight .............. WTPXRP21 879-886
Replicate 22 final exam weight .............. WTPXRP22 887-895
Replicate 23 final exam weight .............. WTPXRP23 896-904
Replicate 24 final exam weight .............. WTPXRP24 905-913
Replicate 25 final exam weight .............. WTPXRP25 914-921
Replicate 26 final exam weight .............. WTPXRP26 922-929
Replicate 27 final exam weight .............. WTPXRP27 930-937
Replicate 28 final exam weight .............. WTPXRP28 938-946
Replicate 29 final exam weight .............. WTPXRP29 947-955
Replicate 30 final exam weight .............. WTPXRP30 956-964
Replicate 31 final exam weight .............. WTPXRP31 965-973
Replicate 32 final exam weight .............. WTPXRP32 974-981
Replicate 33 final exam weight .............. WTPXRP33 982-989
Replicate 34 final exam weight .............. WTPXRP34 990-997
Replicate 35 final exam weight .............. WTPXRP35 998-1006
Replicate 36 final exam weight .............. WTPXRP36 1007-1015
Replicate 37 final exam weight .............. WTPXRP37 1016-1024
Replicate 38 final exam weight .............. WTPXRP38 1025-1033
Replicate 39 final exam weight .............. WTPXRP39 1034-1041
Replicate 40 final exam weight .............. WTPXRP40 1042-1049
Replicate 41 final exam weight .............. WTPXRP41 1050-1058
Replicate 42 final exam weight .............. WTPXRP42 1059-1067
Replicate 43 final exam weight .............. WTPXRP43 1068-1075
Replicate 44 final exam weight .............. WTPXRP44 1076-1083
Replicate 45 final exam weight .............. WTPXRP45 1084-1092
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Replicate 46 final exam weight .............. WTPXRP46 1093-1100
Replicate 47 final exam weight .............. WTPXRP47 1101-1109
Replicate 48 final exam weight .............. WTPXRP48 1110-1118
Replicate 49 final exam weight .............. WTPXRP49 1119-1126
Replicate 50 final exam weight .............. WTPXRP50 1127-1134
Replicate 51 final exam weight .............. WTPXRP51 1135-1143
Replicate 52 final exam weight .............. WTPXRP52 1144-1151
HOUSEHOLD YOUTH QUESTIONNAIRE (HYQ)
GENERAL INFORMATION
Age in months at youth interview ............ HYAITMO 1152-1155
MEC EXAMINATION
GENERAL INFORMATION
Language used by SP in MEC .................. MXPLANG 1156
Session for MEC examination ................. MXPSESSR 1157
Date of MEC exam time in: month ............. MXPTIMO 1158-1159
Day of week of MEC exam ..................... MXPTIDW 1160
Age in months at MEC exam ................... MXPAXTMR 1161-1163
HOME EXAMINATION
GENERAL INFORMATION
Session for home examination ................ HXPSESSR 1164
Date of home exam: month .................... HXPTIMO 1165-1166
Day of week of home exam .................... HXPTIDW 1167
Age in months at home exam .................. HXPAXTMR 1168-1169
HOUSEHOLD FAMILY QUESTIONNAIRE (HFQ)
GENERAL INFORMATION
Version of household family quex ............ HFVERS 1170
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
Family interviewer number ................... HFINTVR 1171-1174
Language of family interview ................ HFLANG 1175
SECTION A. INDIVIDUAL CHARACTERISTICS
State or foreign country of birth ........... HFA6XCR 1176
Highest grade or yr of school completed ..... HFA8R 1177-1178
Marital status .............................. HFA12 1179-1180
Military service ............................ HFA13 1181
SECTION B. HEALTH INSURANCE AND INCOME ASSISTANCE
Any SP covered by Medicare in last month .... HFB1 1182
Covered by Medicare in last month ........... HFB2 1183
Type of Medicare coverage ................... HFB3 1184
Covered by Medicare last mo for hospital .... HFB4 1185
Covered by Medicare last mo for doctor ...... HFB5 1186
Any SP covered by Medicaid in last month .... HFB6 1187
Covered by Medicaid in last month ........... HFB7 1188
Any SP covered by CHAMPUS, etc, last mo ..... HFB8 1189
Covered by CHAMPUS/VA/military last mo ...... HFB9 1190
Any SP cov by other health insur last mo .... HFB10 1191
Covered by other health insur last month .... HFB11 1192
Any plan cover any hospital expenses ........ HFB11A 1193
Any plan cover routine doctor's care ........ HFB11B 1194
Any plan cover dental care (phase 2) ........ HFB11C 1195
Any plan from employer or union (phase2) .... HFB11D 1196
Covered plan pays for operations (ph 1) ..... HFB11E 1197
Refused/limited insur, poor health (ph2) .... HFB12 1198
Insurance coverage check item ............... HFB13 1199
No insurance: unemployed or related(ph1) .... HFB14AB 1200
No insur: poor health, illness, age(ph1) .... HFB14AC 1201
No insurance: can't afford (phase 1) ........ HFB14AD 1202
No insur: dissatisfied w/ previous (ph1) .... HFB14AE 1203
No insurance: don't believe in (phase 1) .... HFB14AF 1204
No insurance: healthy, no need (phase 1) .... HFB14AG 1205
No insurance: some other reason(phase 1) .... HFB14AI 1206
NHANES III Household Youth Data File Index
Including demographic, family, and survey weighting data
------------------------------------------------------------------------
Variable
Description Name Positions
------------------------------------------------------------------------
No insur: refused for health reason(ph2) .... HFB14BA 1207
No insur: not employed,can't afford(ph2) .... HFB14BB 1208
No insur: not employed,not continue(ph2) .... HFB14BC 1209
No insur: employer does not offer (ph 2) .... HFB14BD 1210
No insur:emplyr offers,not eligible(ph2) .... HFB14BE 1211
No insur:emplyr offers,can't afford(ph2) .... HFB14BF 1212
No insur:no believe/not get/no need(ph2) .... HFB14BG 1213
No insurance:some other reason (phase 2) .... HFB14BH 1214
Main reason not covered (phase 1) ........... HFB16A 1215-1216
Main reason not covered (phase 2) ........... HFB16B