September 2000 Food Security Supplement Data File: Technical Documentation
Prepared: November 27, 2001
Revised/Updated: July 17, 2001—release of first draft, August
22, 2001—revised to note logical record length, November 28,
2001—revised to change name to children's food security scale
Overview
This document provides technical information on the Current Population
Survey Food Security Supplement (CPS-FSS) conducted by the U.S.
Census Bureau for the U.S. Department of Agriculture in September
2000.
The CPS-FSS is available from the U.S. Census Bureau in three
formats: ASCII format on CD-ROM, ASCII format via the DataFerrett
system, and SAS transport format via the DataFerrett system.
The
Food Security in the
United States briefing room provides additional documentation,
a facsimile
of the questionnaire, and information on the concepts and history
of the food-security measurement project.
Technical Description
The CD-ROM data file is in ASCII format and consists of 134,856
logical records. The length of each record is 1,115 characters.
Each record represents one person in a surveyed household or one
address that was selected for the core labor force survey but that
either was vacant, was not a residence, could not be contacted,
or refused to participate. Noninterview households (13,198) are
included in the CD-ROM file with their noninterview status indicated.
Interviewed households (47,878) include 121,658 person records.
Households that completed the Food Security Supplement as well as
the labor force survey (40,460) include 103,320 person records.
The DataFerrett
system files do not include noninterview households (but
do include interviewed households with Supplement data missing).
Data
files downloaded from DataFerrett, therefore, exclude noninterview
households and consist of 121,658 records representing 47,878
households.
A subset of variables on each record contains data about the household
of which the person is a part. These variables have the same value
for all persons in the same interview household.
Contents of the Data FileThe file includes data in three general categories:
(1) Monthly labor force survey data and recodes, collected by the
Census Bureau for the Bureau of Labor Statistics. These variables
are described briefly in the data dictionary. For concepts and definitions
underlying these data, users should refer to the technical documentation
for the CPS monthly labor force data available from the Bureau of
Labor Statistics. Included are geographic, demographic, income,
and employment data that may be of interest to those analyzing the
Food Security Supplement data.
(2) Food Security Supplement data, collected by the Census Bureau
for the United States Department of Agriculture. These data consist
of answers by household respondents to questions about household
food expenditures, use of food assistance programs, and experiences
and behaviors related to food security, food insecurity, and hunger.
All of the Food Security Supplement data are household-level data
except for the Supplement person weight.
(3) Food security and hunger scale and status indicators calculated
from the Food Security Supplement data by the Economic Research
Service of the United States Department of Agriculture. These indicate
the screening status of the household, as well as continuous and
categorical measures of food security status. They are all household-level
variables.
Contents of the Food Security Supplement Questionnaire
A facsimile
of the Food Security Supplement questionnaire is available
on the ERS website (address at end of this document) and
on the public-use data file CD-ROM available from the
Census Bureau. Variable names in the data dictionary generally
consist of the prefix HE (household variable, edited)
followed by the question number from the questionnaire.
The major sections are as follows:
(1) Food Spending (HES1-HES8).
(2) Food Assistance Program Participation (HES9-HESP9).
(3) Food Sufficiency and Food Security (HESS1-HESSH5A). This section
includes the 18 food security and hunger questions that are used
to calculate the household food security scale.
(4) Ways of Avoiding or Ameliorating Food Deprivation—Coping
Strategies (HESC1-HESC4).
(5) Minimum Food Spending Needed (HES10-HES12)
Changes from Previous Years' Food Security SupplementsThe following changes were introduced in the 2000 Food Security
Supplement:
- The question on reduced-cost meals for the elderly was split
into two questions (HESP5, HESP5A) to clearly include both meals
delivered to the home as well as meals at a community center or
senior center.
- A question was added to ask about free or reduced-cost food
received at a day care or Head Start program (HESP7A).
- The split ballot test of the two forms of the USDA/NHANES food
sufficiency questions was discontinued. The single-question form
(HESS1) was retained.
- A split ballot test of variants of the first three questions
in the food security scale (HESS2A, HESS3A, and HESS4A) was initiated
for households in rotation 8. The questions were proposed by Health
Canada for national surveys in Canada.
- The split ballot test of individually referenced questions
conducted in 1998 and 1999 was discontinued.
- A split ballot test of follow-ups to six questions in the hunger
and severe hunger series (HESHF2A, HESHF3A, HESHF4A, HESSHF1A,
HESSHF2A, HESSHF4A) was initiated for households in rotation 8.
The test question asks, "In months when [behavior or experience
occurred], how many days did this usually happen?" The 30-day
followup question for these households was skipped.
- A revised method was introduced for asking about the minimum
amount households need to spend for food in order to meet the
needs of the household (HES10, HES11, HES12).
- Three variables based on the children's food security scale
are included in the data file (HRFS12M5, HRFS12M6, HRFS12M7) to
characterize food stress among children. The scale is calculated
from the 8 child-referenced questions in the household food security
scale and did not require any changes to the questionnaire.
Screening of the Food Security Supplement
The Food Security Supplement includes several screens to reduce
respondent burden and to avoid embarrassing respondents by asking
them questions that are inappropriate given other information they
have provided in the survey. The screener variables use information
from the monthly labor force core data as well as from the Food
Security Supplement. Households with incomes above 185 percent of
the poverty threshold (HRPOOR=2, estimated from HUFAMINC and HRNUMHOU)
that responded "no" to HES9 were not asked the questions
on participation in food assistance programs. Households with income
above 185 percent of poverty that registered no indication of food
stress on HES9 or HESS1 were not asked the rest of the questions
in the "Food Sufficiency and Food Security" section or
those in the "Ways of Avoiding or Ameliorating Food Deprivation"
section. There are also two "internal" screeners in the
main food security section (the questions that are used to calculate
the household food security scale). This series of questions is
divided into three blocks. After each of the first two blocks, households
that registered no indication of food stress in the preceding block
are skipped over the rest of the "Food Sufficiency and Food
Security" section.
The screening rules that determine whether a household was asked
the questions in the food security scale varied somewhat during
the first 4 years of fielding the Food Security Supplement. These
different screening procedures biased estimated prevalences of food
insecurity and hunger differently in each year. Adjustments must
be made for these differences to compare prevalences of food security
and hunger across years. This topic is discussed further below under
the heading "Food Security Scales and Screener Variables."
Screeners also were applied based on whether the household included
any children, so that households without children were not asked
questions that refer specifically to children. For this purpose,
persons 17 or younger are classified as children except those who
are household reference persons or spouses of household reference
persons (PERRP=1, 2, or 3). In the 2000 Food Security Supplement,
unlike in previous years, the exception for minor reference persons
and spouses of reference persons was made in the survey instrument
and is, therefore, correctly reflected in the responses in the data
file.
Food Security Scales and Screener Variables
The main purpose of the Food Security Supplement is to provide information
about food security, food insecurity, and hunger in the Nation's
households. Several variables are provided in the data file that
identify the food security status of each household during the previous
12 months. All of these variables are based on responses to a set,
or subset, of 18 questions in the Supplement that are indicators
of food insecurity and hunger. HRFS12M3 is the raw score—a
count of the number of questions affirmed by the household respondent.
HRFS12M4 is the household food security scale score, a continuous
score based on fitting the data to a single-parameter Rasch model
using item calibrations calculated from the 1998 data. Computed
values range from about 1 to 14. Scale scores for households that
affirmed no items cannot be calculated within the Rasch model. These
households are food secure, but the degree of their food security
is not known and may vary widely from household to household. They
are assigned scale scores of -6 to remind users that they require
special handling in analyses that assume linearity of the scale
scores. HRFS12M1 is a categorical variable based on the scale score
that classifies households in three categories: food secure, food
insecure without hunger, and food insecure with hunger. HRFS12M2
is the same as HRFS12M1 except that the food-insecure-with-hunger
category is subdivided to level 1 and level 2 hunger. The level
2 hunger category corresponds operationally with the "Severe
Hunger" category described in Household Food Security in the
United States in 1995: Summary Report of the Food Security Measurement
Project and with the "Food Insecure with Hunger (Severe)"
category described in Guide to Measuring Household Food Security
- 2000, both published by the Food and Nutrition Service.
A second set of food security status variables indicating
the level of food stress among children in the household
is calculated from responses to the eight questions in
the scale that ask specifically about conditions among
the children. The children's food security scale variables
are HRFS12M6 (raw score), HRFS12M7 (Rasch-based scale
score), and HRFS12M5 (2-category children's hunger status
indicator).
The food security variables described above are based
on responses to the 18 food security indicator questions
as they were administered in the 2000 survey. They are
directly comparable to the corresponding variables in
the August 1998 and April 1999 surveys. A second set of
food security scale and status indicators are provided
to facilitate comparisons to years prior to 1998. These
"common screen" variables are adjusted for interyear differences
in survey screening procedures and are comparable to corresponding
variables in all earlier years' CPS-FSS data files. Prevalence
estimates based on these common-screen variables are comparable
across all survey years. The common-screen-based food
security variables are HRFS12C3 (raw score), HRFS12C4
(Rasch-based scale score), HRFS12C1 (three-category food
security status indicator), and HRFS12C2 (4-category food
security status indicator). The common-screen food security
variables are needed because the screening procedures
used in administering the Food Security Supplements varied
somewhat from year to year. In all years, households that
were screened out after a few initial questions are classified
as food secure. However, comparisons across years of the
item responses of households with identical responses
to the preliminary screener variables show that some households
that were screened out under more stringent screening
rules would have been classified as food insecure (or,
in a few cases, even as food insecure with hunger) if
they had not been screened out. The screening procedures,
therefore, bias prevalence estimates of food security
and hunger downward, and the extent of the bias varies
across years. To compare prevalence rates to years prior
to 1998, it is essential to adjust the data from each
year so that it matches, as nearly as possible, a common
set of screening procedures. That is, negative responses
must be imputed to households that would have been screened
out at the initial screener in any year. For surveys prior
to 1998, negative responses also must be imputed to "downstream"
variables for households that would have been screened
out at either of the internal screens that were first
implemented in 1998. Adjustment of the children's food
security scale variables for screening differences is
not necessary. The effects of the different screening
procedures on the measured prevalence of hunger among
children is negligible.
Two screener status variables are provided. HRFS12MS refers to
screening status under the screen that was applied when the survey
was administered (the "maximum-sample screen.") The variable
indicates whether the household was screened out at the initial
screen (before the first of the 18 scale questions), or was screened
out after the first or second blocks of questions, or was not screened
out and was asked all questions. Households that were screened out
at the initial screen without giving a valid response to either
screening question, or who were screened out after the first or
second block without having given a valid response to any of the
questions in the scale are coded as "Missing" (-5) on
HRFS12MS. The corresponding food security scale and status variables
for these households (HRFS12M1 through HRFS12M7) are coded as "No
Response" (-9).
HRFS12CS refers to screening status under the 1995-2000 common
screen. Categories are the same as for the maximum-sample
screen variable, and households that would have been screened
out with no valid responses to any of the indicator questions
under the common screen are coded as "Missing" (-5). Common-screen
food security scale and status variables (HRFS12C1 through
HRFS12C4) for these households are coded as "No Response"
(-9).
Constructing Household Characteristics from Person Records
To compute some household characteristics such as household size,
presence of children, or presence of elderly members, it is necessary
to identify the records of all persons in the same household. Households
are uniquely and completely identified by State of residence (GESTCEN),
household identifier (HRHHID), and household serial suffix (HSERSUF).
Sort records within households by PERRP if the household reference
person record must be the first record in the household. To match
to other months' CPS files, add the HRMIS variable to the household
identification, adjusting one of the files for the difference in
survey month. For matching to the March Annual Demographic Supplement,
HRSERSUF may need to be recoded.
Weights—Estimating Population Distributions
of Person and Household Characteristics
The CPS is a complex probability sample, and interviewed households
as well as persons in those households are assigned weights so that
the full interviewed sample represents the total national noninstitutionalized
population. Initial weights are assigned based on probability of
selection into the sample, and weights are then adjusted iteratively
to match population controls for selected demographic characteristics
at State and National levels. There are two sets of household and
person weights in this data file: (1) labor force survey weights,
(2) Food Security Supplement weights.
The labor force survey weights, HWHHWGT for households and PWSSWGT
for persons, are positive for persons in all interviewed households.
These weights would be appropriate for analyzing whether households
or persons who completed the Supplement differed from those who
declined to complete the Supplement.
About 12 percent of households completed the core labor force survey
but declined to complete the Food Security Supplement. The Supplement
weights, HHSUPWGT for households and PWSUPWGT for persons, are adjusted
for Supplement nonresponse so that the Supplement respondents represent
the national noninstitutionalized population. These weights are
appropriate for estimating household distributions of variables
in the Food Security Supplement, including food security status.
Household weights are attached to all person records in the household.
To estimate household frequency distributions, the sample must be
limited to one record for each household. This is usually accomplished
by limiting the sample to records of household reference persons
(PERRP=1 or 2). Noninterview or nonsupplement households must be
excluded from these analyses based on HRINTSTA or HRSUPINT.
All weight variables have four implied decimal places in the CD-ROM
(the decimal point is not included). Divide the weight variables
by 10,000 for analysis in units or by 10,000,000 for analysis in
thousands of persons or thousands of households. The format of weight
variables downloaded from Ferrett are somewhat unpredictable. Sometimes
they are in units; sometimes they have four implied decimal places.
These should be checked prior to use.
Further Information
Information on the Federal Food Security Measurement Project, and
on survey and measurement issues, is available from:
United States Department of Agriculture, Economic Research Service
Contact Mark Nord 202-694-5433; marknord@ers.usda.gov
United States Department of Agriculture, Food and Nutrition Service
Contact Gary Bickel 703-305-2125; gary.bickel@fns.usda.gov
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