• Component Description
• Quality Assurance & Quality Control
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • FSDHH - Household food security category
  • FSDAD - Adult food security category
  • FSD151 - HH Emergency food received
  • FSQ165 - HH FS benefit: ever received
  • FSQ012 - HH FS benefit: receive in last 12 months
  • FSD230 - HH FS benefit: currently receive
  • FSD162 - HH WIC benefit: receive in last 12 month
  • FSQ760 - HH WIC benefit: received in last 30 days
  • FSQBOX6 - CHECK ITEM
  • FSQ653 - CH WIC benefit: ever received
  • FSD660ZC - CH WIC benefit: currently receive
  • FSD675 - CH WIC benefit: received in infancy
  • FSD680 - CH WIC benefit: received b/w 1-4 yrs old
  • FSD670ZC - CH WIC benefit: # of months received
  • FSQ690 - CH WIC benefit: Mom received while preg.
  • FSQ695 - CH WIC benefit: starting month of preg.
  • FSQBOX7 - CHECK ITEM
  • FSD652ZW - WM WIC benefit: receive in latest preg.
  • FSD672ZW - WM WIC benefit: starting month of preg.
  • FSD652CW - WM WIC benefit: receive post-partum
  • FSQBOX8 - CHECK ITEM
  • FSD660ZW - WM WIC benefit: currently receive
• Appendix 1

National Health and Nutrition Examination Survey

2017-March 2020 Data Documentation, Codebook, and Frequencies

Food Security (P_FSQ)

Data File: P_FSQ.xpt

First Published: February 2022

Last Revised: NA

Component Description

The NHANES program suspended field operations in March 2020 due to the coronavirus disease 2019 (COVID-19) pandemic. As a result, data collection for the NHANES 2019-2020 cycle was not completed and the collected data are not nationally representative. Therefore, data collected from 2019 to March 2020 were combined with data from the NHANES 2017-2018 cycle to form a nationally representative sample of NHANES 2017-March 2020 pre-pandemic data. These data are available to the public. Please refer to the Analytic Notes section for more details on the use of the data.

The 2017-2018 and 2019-2020 food security questionnaires are available on the NHANES website. The Food Security section (variable name prefix FSQ) provides individual and household-level interview data on the following topics:

1. Household food security
In the household interview, an adult responded to the U.S. Food Security Survey Module (US FSSM) questions (Bickel G, et al, 2000). There are 18 items that were asked for households with children under the age of 18 years and 10 items for households without children. The questions refer to all household members, not just NHANES participants. Two categorical household-level variables were created to characterize the overall food security status for the entire household and the adults in the household. The categorical variables derived from these responses are released on each household participant’s record.

A question on household member’s use of emergency foods from food banks, soup kitchens, or other organizations in the last 12 months is also included in this section.

2. Supplemental Nutrition Assistance Program (SNAP)/Food Stamp program benefits
All SNAP/Food Stamp benefits questions were collected at the household level. In 2015-2016, the questionnaire for SNAP/Food Stamp benefits in the household interview was redesigned to obtain a more complete picture of all benefit recipients in the household and these changes continued in the 2017-2018 and 2019-2020 survey cycles. The data collection instruments were modified to identify each household member’s SNAP/Food Stamp benefit receipt status on the household roster. The data were then summarized at the household level.

Household-level data on SNAP/Food Stamp benefits are released on all household participants’ records.   

3. Women, Infants and Children (WIC) program benefits 
Data collected for WIC benefits included two household-level questions as well as six individual-level questions for participants aged birth to 5 years, one individual-level question for children 1-5 years, and four individual-level questions for women aged 12 years and over.

In the household interview, an adult from each family responded to the questions on whether anyone in the household received WIC benefits in the last 12 months. Beginning in 2015-2016, a question on current WIC participation in the last 30 days was added. These household-level questions are released on all household participants’ records.

For children participants, the target age group for the WIC benefit questions was changed from 0-11 to 0-5 years, starting in the NHANES 2015-2016 cycle. Children’s WIC participation data were collected through adult proxy during the household interview as part of the 2017-2018 and 2019-2020 Dietary Behavior and Nutrition questionnaire (DBQ). During a cognitive testing conducted in 2014, considerable recalling errors were observed among proxies for children aged 6-11 years old, which triggered this change in the target group. In addition, starting in 2015-2016, instead of whether these children received benefits in the last 12 months, information was collected on whether they ever received WIC benefits, since the latter provided a preferable time reference for children in this age group. Similarly, information on current participation and WIC participation during various important periods in early childhood, including prenatal, infancy, and 1-4 years old, was also collected and released on the individual participant’s record.

For female participants 12 years and older, a new WIC module was added in 2015-2016 to determine WIC participation for pregnant and postpartum women separately. The questions, which were adapted from the National Center for Education Statistics’ Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), will allow researchers to determine whether a woman participated prenatally and/or postnatally. Women 12 years and older were asked about WIC benefits received during the latest pregnancy, the month of pregnancy when benefits started, and whether benefits were received post-partum. Like previous years, information was also collected on current WIC participation. These questions were administered as part of the 2017-2018 and 2019-2020 Reproductive Health questionnaire (RHQ) during the Mobile Examination Center (MEC) interview, using the Computer-Assisted Personal Interview-CAPI (interviewer administered) system. Due to potential disclosure risk, the WIC benefits data will only be released for women aged 20 years and above in the public dataset. Data for all women 12 years and older will be available in the Research Data Center (RDC) only. Please refer to the Analytic Notes section for more details.

The table in Appendix 1 provides detailed information on each of the three FSQ components described above.

Quality Assurance & Quality Control

The automated interview systems used in NHANES are programmed with built-in consistency checks to reduce data entry errors. All the data were reviewed for accuracy and completeness. NHANES staff reviewed audio recordings of interviews, traveled to field sites to observe interviews, read interviewer comments, and attended training and re-training sessions to maintain the high-quality data.

Data Processing and Editing

Frequency counts were checked, "skip" patterns were verified, and the reasonableness of question responses was reviewed. Edits were made to some variables to ensure the completeness, consistency, and analytic usefulness of the data. Edits were also made, when necessary, to address data disclosure concerns.

FSDHH, FSDAD (Household and adult food security category)
Eighteen FSSM questions were asked of households with children under the age of 18. Ten questions were asked of households without children. Two categorical variables, each with four response levels, were created based on the number of affirmative responses for those questions. These categorical variables could be used to characterize the overall food security status for the entire household and the adults in the household. The algorithms used to derive these categorical variables are described below:

FSDHH (Household food security category):

Count affirmative responses in these 18 items: FSD032a, FSD032b, FSD032c, FSD032d, FSD032e, FSD032f, FSD041, FSD052, FSD061, FSD071, FSD081, FSD092, FSD102, FSD111, FSD122, FSD132, FSD141, and FSD146. Derive the codes as the following:

1 = Household full food security: no affirmative response in any of these items.
2 = Household marginal food security: 1-2 affirmative responses.
3 = Household low food security: 3-5 affirmative responses for household without children under the age of 18; 3-7 affirmative responses for household with children.
4 = Household very low food security: 6-10 affirmative responses for household without children under the age of 18; 8-18 affirmative responses for household with children.

Households with children where no valid response was provided to any of the questions about children’s food security were classified using the specifications for households without children.

FSDAD (Adult food security category):

Count affirmative responses in these 10 items: FSD032a, FSD032b, FSD032c, FSD041, FSD052, FSD061, FSD071, FSD081, FSD092, and FSD102. Derive the codes as the following:

1 = Adult full food security: no affirmative response in any of these items.
2 = Adult marginal food security: 1-2 affirmative responses.
3 = Adult low food security: 3-5 affirmative responses.
4 = Adult very low food security: 6-10 affirmative responses.

FSD165, FSQ012, FSD230 (variables for SNAP/Food Stamp benefits)
Information on the receipt of SNAP/Food Stamp benefits by any household members was provided in the present file: ever (FSQ165), received in the last 12 months (FSQ012), and currently receiving (FSD230). Receipt of SNAP/Food Stamp benefits by all individuals residing in the household, both survey and non-survey participants, was included. In households with more than one family where there were inconsistencies across families, all data were reviewed and reconciled.

FSD230 (Currently receive SNAP/Food Stamp benefits)
Prior to 2015-2016, the question on whether any members of the household currently receive SNAP/Food Stamp benefits (i.e., FSQ230) was only asked when the respondent refused to answer, did not know the exact date (day, month, and year) that the household last received SNAP/Food Stamp benefits, or the date reported was more than 30-days prior to the interview day. FSD230 was then derived from reported benefit receiving date (if the reported last benefits receiving date was within 30 days prior to the interview), or the information reported in question FSQ230. Since 2015-2016, the question (i.e., FSQ755) was directly asked to all family respondents and released in FSD230. Respondents with affirmative answers to FSQ755 were followed up with a question asking them to identify all persons living in the household who are currently receiving benefits from a household roster.

FSD162 (receive WIC benefits in the last 12 months)
This variable indicates whether there is any member of the household who received benefits from WIC in the last 12 months. It is derived for all households that responded to the FSQ section of the family questionnaire, regardless of WIC program eligibility of household members.

FSD652ZW (women received WIC benefits during latest pregnancy)
Information on WIC participation by women during their current (FSQ652a) or last (FSQ652b) pregnancy was obtained. The combined information is included in FSD652ZW.

FSD660ZW (women currently received WIC benefits)
This question was asked of female participants who were pregnant or 0-24 months postpartum at the time of interview. The postpartum screening criterion for this question was added in 2007-2008 to better classify eligibility for WIC benefits and included women 0-2 years postpartum by calculating the differences in years between the reported current age and the age of last delivery. The questionnaire instrument was updated again in 2015-2016 to improve the classification of categorical WIC eligibility by adding a question specifically asking the year and month of the last delivery and comparing those with the interview date.

Analytic Notes

The COVID-19 pandemic required suspension of NHANES 2019-2020 field operations in March 2020 after data were collected in 18 of the 30 survey locations in the 2019-2020 sample. Data collection was cancelled for the remaining 12 locations. Because the collected data from 18 locations were not nationally representative, these data were combined with data from the previous cycle (2017-2018) to create a 2017-March 2020 pre-pandemic data file. A special weighting process was applied to the 2017-March 2020 pre-pandemic data file. The resulting sample weights in the present file should be used to calculate estimates from the combined cycles. These sample weights are not appropriate for independent analyses of the 2019-2020 data and will not yield nationally representative results for either the 2017-2018 data alone or the 2019-March 2020 data alone. Please refer to the NHANES website for additional information for the NHANES 2017-March 2020 pre-pandemic data, and for the previous 2017-2018 public use data file with specific weights for that 2-year cycle.

NHANES has assessed household food security with the U.S. Food Security Survey Module (US FSSM) since 1999. Similar modules have been used in various surveys, including the Census Bureau's Current Population Survey (CPS) and a growing number of State, local, and regional studies, such as the California Health Interview Survey (CHIS). For more information on food security measurement, please refer to the USDA's website at: http://www.ers.usda.gov/topics/food-nutrition-assistance/food-security-in-the-us/measurement.aspx.

The NHANES household interview included two questionnaires: a sample participant questionnaire to collect information regarding each individual survey participant’s personal health status, and a family questionnaire to collect information at the family level, such as total income for the family, food availability in the family, etc. The sample participant questionnaire was answered by participants themselves (adult proxy for child under 16 years old). The family questionnaire required an adult family member, preferably the head of the family, to respond to these questions for the entire family. The information on household food security status and SNAP/Food Stamp program as well as WIC program benefits in the FSQ section were collected as part of this family questionnaire.

Due to potential disclosure risk, this file does not include data of WIC benefit related variables for females less than 20 years old. For female participants 12-19 years old, records are coded as missing for the following variables: FSD652ZW, FSD672ZW, FSD652CW, and FSD660ZW. The complete data file containing all variables for females 12 years and older (P_FSQ_R) is available through the NCHS Research Data Center.

FSQ data were collected in the household and in the MEC. For data items collected in the household interview, the interview sample weights may be used in their analysis. However, if the data analysis requires merging of data collected in the household with data collected in the MEC, examination sample weights should be used for analyses. The recommended weights for each individual component in the FSQ section are listed in the table in Appendix 1.

Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues. Both are available on the NHANES website.

Disclosure risk and issues pertaining to confidentiality protection prevent NCHS from releasing all of the NHANES FSQ variables publicly. Additional information and instructions for requesting use of these data are available through the NCHS RDC.

References

• Guide to Measuring Household Food Security (Revised 2000) | Food and Nutrition Service (usda.gov). Available from: https://fns-prod.azureedge.net/sites/default/files/FSGuide.pdf

Codebook and Frequencies