Vital and Health Statistics

Series 1, Number 60 October 2017

Linkage of 1999–2012 

National Health Interview 

Survey and National Health 

and Nutrition Examination 

Survey Data to 

U.S. Department of Housing 

and Urban Development 

Administrative Records
Copyright information

All material appearing in this report is in the public domain and may be 

reproduced or copied without permission; citation as to source, however, is 

appreciated.

Suggested citation

Lloyd PC, Helms VE, Simon AE, et al. Linkage of 1999–2012 National Health 

Interview Survey and National Health and Nutrition Examination Survey data 

to U.S. Department of Housing and Urban Development administrative records. 

National Center for Health Statistics. Vital Health Stat 1(60). 2017.

Library of Congress Cataloging-in-Publication Data

Names: National Center for Health Statistics (U.S.), issuing body.

Title: Linkage of 1999-2012 National Health Interview Survey and National 

 Health and Nutrition Examination Survey data to U.S. Department of Housing 

 and Urban Development administrative records.

Other titles: Vital and health statistics. Ser. 1, Programs and collection 

 procedures ; no. 60. | DHHS publication ; no. 2018-1336. 0276-4733

Description: Hyattsville, Maryland : U.S. Department of Health and Human 

 Services, Centers for Disease Control and Prevention, National Center for 

 Health Statistics, October 2017. | Series: Vital and health statistics. 

 Series 1, Program and collection procedures ; Number 60 | Series: DHHS pub 

 ; number 2018-1336 | "October 2017." | Includes bibliographical references.

Identifiers: LCCN 2017045165| ISBN 9780840606853 (pbk.) | ISBN 0840606850 

 (pbk.)

Subjects: | MESH: National Health Interview Survey (U.S.) | National Health 

 and Nutrition Examination Survey (U.S.) | United States. Department of 

 Housing and Urban Development. | Health Surveys--methods | Records as 

 Topic | United States Government Agencies | United States

Classification: LCC RA407.3 | NLM W2 A N148va no. 60 2017 | DDC 614.4/

 273--dc23 LC record available at https://lccn.loc.gov/2017045165

For sale by the U.S. Government Printing Office 

Superintendent of Documents 

Mail Stop: SSOP 

Washington, DC 20402–9328 

Printed on acid-free paper.
Vital and Health Statistics

Series 1, Number 60

Linkage of 1999–2012 National 

Health Interview Survey and 

National Health and Nutrition 

Examination Survey Data to 

U.S. Department of Housing 

and Urban Development 

Administrative Records

Programs and Collection Procedures

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Center for Health Statistics

Hyattsville, Maryland 

October 2017 

DHHS Publication No. (PHS) 2018–1336
National Center for Health Statistics

Charles J. Rothwell, M.S., M.B.A., Director

Jennifer H. Madans, Ph.D., Associate Director for Science

Office of Analysis and Epidemiology

Irma E. Arispe, Ph.D., Director

Makram Talih, Ph.D., Associate Director for Science
iii

Contents 

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

NHIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

NHANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

HUD Administrative Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Data Linkage Approval, Eligibility, and Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Linkage Approval and Eligibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Linkage Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Linked NCHS–HUD Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

General Description of Linked Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Access to Linked NCHS–HUD Data Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Analytic Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Sample Weights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Analyses Using Linked NCHS–HUD Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Descriptive Analyses of Linked NHIS–HUD and NHANES–HUD Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Published Research Papers Using NCHS Surveys Linked to HUD Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Appendix I. U.S. Department of Housing and Urban Development’s Largest Housing Assistance Programs . . . . . . . . . . . . 21

Appendix II. Summary of Linked National Center for Health Statistics–U.S. Department of Housing

and Urban Development Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Appendix III. Data Variable Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Appendix IV. Evaluation of NCHS–HUD Data Linkage: Comparison With HUD Program Recipients . . . . . . . . . . . . . . . 25
iv

Detailed Tables

1. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: 

National Health Interview Survey, 1999–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: 

National Health and Nutrition Examination Survey, 1999–2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3. Linked NCHS–HUD file sample size and percentage of linked survey participants with concurrent HUD

enrollment within 1, 2, and 3 years of survey interview, by survey and age at interview. . . . . . . . . . . . . . . . . . . 15

4. Unweighted sample size and weighted percent distribution of ever-linked 2008–2012 NHIS–HUD participants 

aged 0–17 years, by selected sociodemographic and health characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 17

5. Unweighted sample size and weighted percent distribution of ever-linked 2008–2012 NHIS–HUD participants 

aged 18 and over, by selected sociodemographic and health characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 18

6. Unweighted sample size and weighted percent distribution of ever-linked 2009–2012 NHANES–HUD participants 

aged 0–17 years, by selected sociodemographic and health characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 19

7. Unweighted sample size and weighted percent distribution of ever-linked 2009–2012 NHANES–HUD participants 

aged 18 and over, by selected sociodemographic and health characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 20

Text Figures

1. Process used to link National Center for Health Statistics survey data to U.S. Department of Housing and 

Urban Development administrative data sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Temporal alignment of National Center for Health Statistics surveys linked to U.S. Department of Housing and 

Urban Development administrative data files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Appendix Tables

I. Linked NCHS–HUD data files: Name, population, and description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

II. Number and percent distribution of concurrently linked 2012 NHIS–HUD participants and 2012 

HUD-assisted tenants, by HUD program and selected HUD-collected demographic characteristics. . . . . . . . . . . . . 26

III. Number and percent distribution of concurrently linked 2009–2012 NHANES–HUD participants and 

2009–2012 HUD-assisted tenants, by HUD program and selected HUD-collected demographic characteristics . . . . . . 29

Appendix Figures

I. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants,

by HUD housing category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

II. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants,

by sex and age group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

III. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants,

by percentage of households with disabled or elderly persons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

IV. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants,

by household characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

V. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD 

participants, by HUD housing category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

VI. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD 

participants, by sex and age group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

VII. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD 

participants, by percentage of households with disabled or elderly persons . . . . . . . . . . . . . . . . . . . . . . . . . 31

VIII. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD 

participants, by household characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
v

Acknowledgments

The authors gratefully acknowledge 

the following persons for their 

contributions to the success of the 

National Center for Health Statistics 

(NCHS)–U.S. Department of Housing 

and Urban Development (HUD) data 

linkage project: Peter Meyer, Sonali 

Sinha, and Pei-Lu Chiu of NCHS for 

previous research in linking National 

Health Interview Survey and HUD data; 

Clinton Thompson, Deborah Ingram, and 

Eric Miller of NCHS for careful review 

and feedback on the report; Dean Judson 

of NCHS for methodological guidance in 

developing the linkage-eligible adjusted 

sample weights; Fred Selck of NCHS 

for leading the data linkage project 

during its early stages; Jesse Bassich of 

NCHS for programming assistance; Lynn 

Rodgers and Pramod Pamnani of HUD 

for programming expertise in creating 

the HUD administrative data file; Lydia 

Taghavi of HUD for programming 

support; Brent Mast and Carol Leming of 

HUD for providing input on the contents 

of the linked file; Donna Miller and Eve 

Powell-Griner of NCHS for providing 

input on confidentiality and privacy of 

linked survey participants; and Amy 

Branum and Makram Talih of NCHS 

for their careful review of this report. 

The authors gratefully acknowledge the 

editorial staff for their critical review 

and preparation of this report, which was 

edited and produced by the NCHS Office 

of Information Services, Information 

Design and Publishing Staff: Jane Sudol 

edited the report, and typesetting and 

graphics were done by Odell D. Eldridge 

(contractor).
Page 1 

Introduction

The National Center for Health 

Statistics (NCHS) is the nation’s principal 

agency providing health statistics to 

identify and address health issues. To 

maximize the scientific value of NCHS 

population-based surveys, the agency 

has developed a data linkage program 

that links health survey data to vital 

and administrative data sources. Linked 

data files enable researchers to use 

longitudinal data from administrative 

databases or mortality data in 

combination with cross-sectional data 

to examine and provide more insight on 

factors that influence disability, health 

care utilization, morbidity, and mortality 

among different U.S. subpopulations. 

Two NCHS national health 

surveys—the National Health Interview 

Survey (NHIS) and the National 

Health and Nutrition Examination 

Survey (NHANES)—monitor the 

health and well-being of the civilian 

noninstitutionalized population of the 

United States. Through a collaborative 

interagency agreement between NCHS 

and the U.S. Department of Housing and 

Urban Development (HUD), participant 

records from these two NCHS surveys 

were linked to administrative data from 

HUD’s largest federal housing assistance 

programs, which include Housing Choice 

Vouchers (HCVs), multifamily (MF), and 

public housing (PH) programs. The HUD 

administrative files contain housing, 

income, and household characteristics 

as well as program participation data for 

HCV, MF, and PH program recipients in 

all 50 states and the District of Columbia. 

This report summarizes the data 

sources and linkage methods used to 

create the linked NCHS–HUD data 

files. It provides linkage rates for the 

1999–2012 NHIS–HUD and NHANES–

HUD linked files and the percentage 

distribution of selected characteristics 

among linked survey participants. 

Appendix I contains a summary of 

the HUD programs included in linked 

data sets. Appendix II summarizes the 

contents of the linked NCHS–HUD data 

files. Appendix III provides details about 

the files and a description of some key 

Linkage of 1999–2012 National 

Health Interview Survey and 

National Health and Nutrition 

Examination Survey Data to 

U.S. Department of Housing 

and Urban Development 

Administrative Records

by Patricia C. Lloyd, National Center for Health Statistics; Veronica E. 

Helms, U.S. Department of Housing and Urban Development; Alan E. 

Simon, Cordell Golden, James Brittain, Eileen Call, and Lisa B. Mirel, 

National Center for Health Statistics; Barry L. Steffen, Jon Sperling, 

and Elizabeth C. Rudd, U.S. Department of Housing and Urban 

Development; Jennifer D. Parker, National Center for Health Statistics; 

and Carol S. Star, U.S. Department of Housing and Urban Development

Background

The National Center for Health 

Statistics (NCHS) provides statistical 

information to guide actions and 

policy to improve the health of 

the American people. NCHS has 

developed a data linkage program 

that links its cross-sectional health 

survey data to information from vital 

and administrative data sources. 

Through a collaborative interagency 

agreement between NCHS and 

the U.S. Department of Housing 

and Urban Development (HUD), 

participants in two national health 

surveys administered by NCHS were 

linked to administrative data from HUD.

Methods

This report describes and 

evaluates the data linkage of 

1999–2012 National Health Interview 

Survey (NHIS) and National Health 

and Nutrition Examination Survey 

(NHANES) to administrative records 

from HUD through 2014. A brief 

overview of the data sources, 

methods used for linkage, details of 

the resulting linked data files, and 

analytic considerations are provided.

Conclusions

The NCHS–HUD linkage 

demonstrates the feasibility of linking 

population health survey data to 

administrative records from federal 

programs and enhances two NCHS 

population health surveys, NHANES 

and NHIS, by allowing examination of 

the relationship between housing and 

health.

Keywords: record linkage • linked 

data • HUD • housing • NHIS •

NHANES

Abstract
Page 2  Series 1, No. 60

variables for researchers to consider 

when using the linked NCHS–HUD data. 

Appendix IV describes an evaluation 

comparing characteristics among linked 

2012 NHIS–HUD and 2009–2012 

NHANES–HUD participants to those of 

HCV, MF, and PH program recipients, 

using HUD administrative data from the 

same time period.

Data Sources

NHIS

NHIS is a cross-sectional household 

interview survey designed to monitor the 

health of the civilian noninstitutionalized 

U.S. population through the collection 

and analysis of data on a broad range of 

health topics (1). NCHS has conducted 

NHIS continuously since 1957, and the 

content of the survey is periodically 

updated. The sampling plan follows a 

multistage area probability design that 

permits the representative sampling of 

households and noninstitutional group 

quarters (e.g., college dormitories). The 

sampling plan is redesigned after every 

decennial census. The NHIS 1995–2005 

survey design oversampled black as well 

as Hispanic persons; the 2006–2012 

design oversampled black, Hispanic, and 

Asian persons (2). 

Demographic and basic health 

information are collected on everyone 

in the household. For the years of data 

used for linkage, the Core questions 

have remained largely unchanged. 

This allows for trend analyses and 

for data from more than 1 year to be 

pooled to increase sample size for 

analytic purposes. For 1999–2012 

NHIS, the Core section contains four 

major components: Household, Family, 

Sample Adult, and Sample Child. The 

Household component collects limited 

demographic information on all of the 

individuals in a particular household. The 

Family component verifies and collects 

additional demographic information on 

each member from each family in the 

household and collects data on topics 

including health status and limitations, 

injuries, health care access and 

utilization, health insurance, and income 

and assets. 

From each family, one sample adult 

(not necessarily the head of household) 

and one sample child (if any children 

under age 18 years are present) are 

randomly selected, and detailed survey 

data are collected on specific health 

topics using the Sample Adult Core and 

the Sample Child Core questionnaires. 

Data for the Sample Child questionnaire 

is obtained from a knowledgeable adult 

in the household, usually a parent.

Data are collected through a 

personal household interview conducted 

by interviewers employed and trained 

by the U.S. Census Bureau according 

to procedures specified by NCHS. A 

computer-assisted personal interviewing 

(CAPI) mode using a laptop computer 

has been used since 1997. For more 

information on NHIS, visit: https://www.

cdc.gov/nchs/nhis.htm. 

NHANES

NHANES utilizes interviews, 

laboratory tests, and physical 

examinations to assess the health 

and nutritional status of civilian 

noninstitutionalized adults and 

children in the United States (3). The 

survey currently includes a nationally 

representative sample of about 5,000 

persons in about 15 counties across 

the country each year. Oversampled 

subgroups for 1999–2006 included 

non-Hispanic black as well as MexicanAmerican persons; low-income persons 

of non-Hispanic white and other race and 

ethnicity (beginning in 2000); adolescents 

aged 12–19; and non-Hispanic white 

and other persons aged 70 and over. 

Oversampled subgroups for 2007–2010 

included all Hispanic as well as nonHispanic black persons; low-income 

persons of non-Hispanic white and other 

race and ethnicity; and non-Hispanic 

white and other persons aged 80 and 

over (4,5). Beginning with the NHANES 

2011–2012 cycle, non-Hispanic Asian 

persons were also oversampled in 

addition to the ongoing oversample of 

subgroups from 2007–2010 (6).

Health interviews are conducted 

in participants’ homes. Physical 

examinations and health measurements 

are performed in a specially designed 

and equipped mobile examination center 

(MEC), which travels to locations 

throughout the country. The study team 

consists of a physician, medical and 

health technicians, and dietary and health 

interviewers. 

The NHANES interview includes 

demographic, socioeconomic, dietary, 

and health-related questions. The 

examination component consists of 

medical, dental, and physiological 

measurements, as well as laboratory tests. 

Survey findings are used to determine 

the prevalence of major diseases and risk 

factors for diseases. NHANES findings 

are also the basis for national standards 

for such measurements as height and 

weight and for national growth charts. 

Data are also collected on chronic and 

previously undiagnosed conditions. 

More information on NHANES is 

available from: https://www.cdc.gov/

nchs/nhanes.htm.

HUD Administrative Data

HUD’s largest housing assistance 

programs, which include Housing Choice 

Vouchers (HCVs), multifamily (MF) 

programs, and public housing (PH) 

programs, are included in the linked 

NCHS–HUD data. MF programs provide 

affordable housing through contracts 

with private owners of apartment 

buildings. HCV and PH programs 

are managed by local public housing 

agencies (PHAs), which oversee data 

collection and manage housing assistance 

program implementation. Buildings of 

PH programs are owned by PHAs. The 

HCV program gives tenants a voucher 

that covers part of their rent in a privatemarket unit. Administrative data for 

HUD-assisted households are submitted 

by housing providers. Additional 

information about these programs is 

provided in Appendix I and the Analytic 

Guidelines (7).
Series 1, No. 60  Page 3 

Public and Indian Housing 

Information Center 

Local PHAs collect and 

electronically submit information 

to the Public and Indian Housing 

Information Center (PIC) for households 

receiving HCVs or PH assistance. Each 

occasion that data are entered into the 

system is referred to as a transaction. 

The administrative purpose of the 

periodic transactions is to ensure that 

tenant rent contributions, which are 

based on income, are determined 

accurately. Information collected on the 

administrative forms include: dates of 

enrollment and participation, program 

recertification, family characteristics, 

detailed income and asset information 

for all household members, and an 

estimate of the family's anticipated income 

for the next 12 months, including sources 

of that income. More information about 

recertification for HCV and PH programs is 

available from the Analytic Guidelines (7).

Tenant Rental Assistance 

Certification System

Owner/agents and contract 

administrators of MF units collect and 

electronically submit information to HUD 

through the Tenant Rental Assistance 

Certification System (TRACS). As with 

PIC, TRACS collects dates of enrollment 

and participation, program recertification, 

detailed income and asset information for 

all household members, and an estimate 

of the family's anticipated income for the 

next 12 months, including sources of that 

income. Also like PIC, each occasion that 

data are entered into the system is referred 

to as a transaction. More information 

about TRACS and recertification for MF 

programs is available from the Analytic 

Guidelines (7).

HUD transaction dates included 

in NCHS–HUD administrative 

period

For the linkage described in 

this report, HUD programming staff 

created an extract of HUD transactions 

for recipients of HCV, MF, and PH 

programs based on PIC and TRACS, 

referred to as the Transaction File. HUD 

administrative records included in the 

Transaction File were restricted to MF 

program transactions occurring June 30, 

1996–December 31, 2014, and HCV 

and PH program transactions occurring 

December 1, 1999–December 31, 2014. 

These program transaction periods are 

referred to as the linked NCHS–HUD 

administrative period.

Data Linkage 

Approval, Eligibility, 

and Process 

Linkage Approval and 

Eligibility

All NCHS data linkage activities are 

reviewed and approved by the NCHS 

Research Ethics Review Board (ERB). 

The NCHS Research ERB, which 

functions similar to an Institutional 

Review Board (IRB), is an appointed 

ethics review committee that ensures 

research involving human participants 

and the welfare of study participants 

conform to federal regulations. The 

NCHS–HUD linkage was reviewed and 

approved by the NCHS Research ERB.

Survey data and HUD administrative 

records were linked only for NCHS–

HUD linkage-eligible survey participants. 

NCHS determined eligibility for this 

linkage based on whether the survey 

participant provided certain data elements 

necessary for linkage, including Social 

Security number (SSN), sex, month of 

birth, year of birth, first name, and last 

name; did not refuse data linkage; and 

did not refuse to respond to questions 

about receiving rental assistance (NHIS 

only). The question about receiving rental 

assistance was asked only of families 

reporting that they lived in a rental 

property. Very few families living in a 

rental property refused to answer the 

question about receiving rental assistance 

(less than 1% in each of the 1999–2012 

NHIS survey years). NCHS–HUD 

linkage eligibility is distinct from HUD 

program eligibility; the latter defines 

whether a person meets eligibility criteria 

to receive HUD housing assistance 

through HCVs and related programs, 

MF programs, or PH programs. More 

information about HUD eligibility 

criteria is available from the HUD 

website: https://www.huduser.gov/portal/

home.html.

The process for determining linkage 

eligibility and collecting personally 

identifiable information (PII) varied 

by NCHS survey and year (cycle). For 

NHANES, PII was consistently collected 

during the time frame used for linkage, 

but the process for obtaining consent 

for record linkage varied across the 

survey cycles. For 1999–2008 NHANES 

participants, refusal to provide an SSN 

was considered an implicit refusal 

for record linkage. For 2009–2012 

NHANES, participants were explicitly 

asked for consent to be included in record 

linkage activities during the informed 

consent process prior to interview. 

Participants who provided an affirmative 

response to the linkage question were 

considered linkage-eligible, conditional 

on having sufficient PII.

For NHIS, changes over time in the 

process for collecting PII and the addition 

of a question to obtain explicit consent 

for linkage meant that the criteria for 

linkage eligibility varied by survey year. 

For 1999–2006, the full nine-digit SSN 

(SSN9) was requested. For 1999–2001, 

SSN9 was requested for all NHIS 

participants. For 2002–2003, SSN9 was 

requested for only the family respondent. 

For 2004–2006, SSN9 was requested 

for the NHIS family respondent, sample 

adult, and sample child. For these years, 

if participants refused to provide SSNs, 

they were implicitly considered to have 

refused record linkage. During that time 

period, the refusal rate for providing 

SSN increased, which reduced the 

number of NHIS participants eligible 

for record linkage (8). In an attempt to 

counter the decline in linkage eligibility 

rates, research was conducted at NCHS 

to assess the accuracy of National 

Death Index matches using partial SSN 

and other PII. The research assessed 

algorithms using the last four and last 

six digits of SSNs. The results provided 

sufficient evidence to support changes in 

how NHIS collected SSNs for linkage 

(9). Beginning in 2007, NHIS attempted 

to decrease linkage refusal rates by 

adding a short introduction before asking 
Page 4  Series 1, No. 60

for SSN during the interview, requesting 

only the last four SSN digits (SSN4) 

instead of all nine and asking participants 

for their explicit permission to link to 

administrative records if SSN4 had not 

been provided (8). Also at this time, the 

NCHS Research ERB determined that 

for NHIS 2007 forward, only primary 

respondents (sample adult and sample 

children) would be eligible for linkage to 

administrative records. 

NCHS survey participants under 

age 18 at the time of the survey are 

considered linkage-eligible if the abovementioned linkage eligibility criteria 

are met and consent is provided by 

their parent or guardian at the time of 

the survey. Once the child participant 

becomes an adult, however, they do not 

have the opportunity to provide or deny 

consent for linking their survey data 

to administrative data based on their 

experience as an adult. In accordance 

with NCHS Research ERB guidelines, 

the linked NCHS–HUD data of child 

participants are available only for 

records that occurred prior to the survey 

participant’s 18th birthday. For example, 

a 15-year-old linkage-eligible survey 

participant of NHIS 2005 can be linked to 

HUD administrative records. Linked data 

containing HUD administrative data for 

2007 and earlier years could be accessed 

by a researcher and included in analyses 

because the child survey participant 

would have been under age 18 during this 

time. However, NCHS is not authorized 

to provide researchers access to HUD 

administrative records for that child 

survey participant from 2008 through 

2012 because the child survey participant 

would have been aged 18 or older. 

Table 1 presents the total number of 

1999–2012 NHIS participants for each 

survey year and age group (0–17 years, 

18–39, 40–64, and 65 and over), the 

number who were eligible for linkage, 

the percentage eligible out of the total 

sample, the number who were linked, 

and the percentage who were linked out 

of those eligible for linkage. Data are 

presented for all NHIS participants, both 

sample adults and sample children. Table 

2 shows similar results for 1999–2012 

NHANES participants. Data are presented 

for all NHANES participants and for 

those who were examined in the MEC.

Linkage Process

Figure 1 presents the overall process 

for linking NCHS survey data to HUD 

administrative data. HUD provided a 

data file, referred to as the HUD finder 

file, containing PII (e.g., SSN, first and 

last name, sex, date of birth, a unique 

HUD-created identification [ID], and 

a sequence number to identify specific 

transactions) of individual HCV, MF, 

or PH program recipients. NCHS staff 

verified that the SSNs on the HUD files 

were valid before linking to a file of 

1999–2012 NHIS and NHANES linkageeligible survey participants. For example, 

if an SSN contained fewer than nine 

digits; nonnumeric values; the first three 

digits “000,” “666,” or in the 900 series; 

the second group of two digits as “00”; or 

the third group of four digits as “0000,” 

it was not considered valid. For survey 

participants who did not provide a valid 

SSN yet did not refuse to provide their 

SSN, SSN9 was extracted from their 

Medicare Health Insurance Claim (HIC) 

number, if provided. SSN9 was extracted 

from the Medicare HIC number only 

if the survey participant was identified 

as the primary claimant for Medicare 

benefits. 

The linkage was predominantly 

deterministic or rules-based, meaning that 

a set of criteria had to be met for a pair 

of records to be linked. Two approaches 

were used to link NCHS survey data to 

HUD administrative records. The first 

approach was used for NCHS survey 

years when the SSN9 was collected from 

survey participants (1999–2006 NHIS 

and all NHANES cycles). This approach 

linked survey participants to HUD 

administrative records by matching on 

valid SSN9, year of birth, month of birth, 

and sex. 

The second approach accommodated 

the NHIS survey years when SSN4 

was collected. This approach matched 

on SSN4, year of birth, month of birth, 

sex, first name, last name, and day of 

 

NOTE: NCHS is National Center for Health Statistics; HUD is U.S. Department of Housing and Urban Development.

SOURCES: NCHS, National Health Interview Survey and National Health and Nutrition Examination Survey, 1999–2012, 

data linked to HUD administrative records, 1996–2014.

Figure 1. Process used to link National Center for Health Statistics survey data to 

U.S. Department of Housing and Urban Development administrative data sources
Series 1, No. 60  Page 5 

birth, thus incorporating first and last 

names and day of birth into the matching 

criteria. Agreement on first name and 

last name was based on exact spelling 

matches or, because spelling variants 

of names are common, was based on 

the way a name sounds rather than how 

it is spelled. The sound-alike systems 

included both a variation of the New 

York State Identification Intelligence 

System (NYSIIS) and the Soundex 

algorithm (10). NYSIIS converts a name 

to a phonetic coding. For example, 

records with last names Smith and 

Smyth received equivalent NYSIIS 

codes, and both would be selected as a 

potential match for an NCHS submission 

with Smith (or Smyth) as a last name. 

Similarly, Soundex is a phonetic 

algorithm for indexing names by sound, 

as pronounced in English. The goal is for 

homophones to be encoded to the same 

representation so that they can agree 

despite minor differences in spelling. 

Specifically, the second approach linked 

survey participants to administrative 

records based on matching the last four 

digits of SSN, year of birth, month of 

birth, sex, and meeting at least one of the 

following conditions:

● Soundex of first names and last 

names agree and are not missing 

● NYSIIS of first names and last 

names agree and are not missing

● Soundex of nonmissing first names 

agree and day of birth agree 

● Soundex of nonmissing last names 

agree and day of birth agree 

● NYSIIS of nonmissing first names 

agree and day of birth agree 

● NYSIIS of nonmissing last names 

agree and day of birth agree 

● Soundex first name agrees with 

Soundex last name and Soundex 

last name agrees with Soundex first 

name 

● NYSIIS first name agrees with 

NYSIIS last name and NYSIIS last 

name agrees with NYSIIS first name

NCHS participants whose data fields 

matched the equivalent administrative 

fields using either of the two approaches 

were identified as linked records. 

To increase the likelihood of finding 

a match, multiple or alternate submission 

records were used for each linkageeligible NCHS survey participant based 

on variations of names. HUD records 

could be matched to any or all of the 

submission records created for a survey 

participant. For example, the name 

“Beth” may be a nickname for a formal 

name like “Elizabeth.” In this situation, 

a record for “Beth” and a record for 

“Elizabeth” were created and submitted 

for linkage.

Once the linkage was performed 

and the best-matched record was 

selected, NCHS created an NCHS finder 

file containing the HUD-created ID 

and binary indicator flags for survey 

participants who were linked to the HUD 

administrative files for HCV, MF, or 

PH program recipients through 2014. 

This file was delivered to HUD, and 

HUD programming staff prepared and 

delivered to NCHS a single transactionslevel file containing data summarized 

for the person’s household as well as 

data summarized for the individual HUD 

housing assistance recipients who were 

linked to NCHS survey participants. 

NCHS programming staff ensured 

that all linked survey participants 

identified in the linkage process were 

returned in the transaction file. NCHS 

staff edited the HUD Transaction File to 

resolve discrepancies with linked records 

so that the final transaction file met ERB 

guidelines. The final linked transaction 

file served as the basis for creating the 

linked files. 

Linked NCHS–HUD 

Data

General Description of 

Linked Data Files 

The linked NCHS survey data and 

HUD administrative data were used 

to produce 12 separate data files. Two 

public-use feasibility files, one for 

the 1999–2012 NHIS and one for the 

1999–2012 NHANES, are available on 

the NCHS data linkage website: 

https://www.cdc.gov/nchs/data-linkage/

index.htm. Ten restricted-use files, 

consisting of the transaction and 

concurrency files, seven separate episode 

files, and a weights file, are available only 

through the NCHS Research Data Center 

(RDC). Appendix Table I describes 

each of the files that compose the linked 

NCHS–HUD data. Data documentation, 

including the Analytic Guidelines (7) and 

Data Dictionary (11), feasibility files, 

and sample read-in software programs to 

import the feasibility files, can be found 

on the NCHS website: https://www.cdc.

gov/nchs/data-linkage/hud.htm. Details 

about each of the linked files are provided 

in the following section.

NHIS–HUD and NHANES–

HUD public-use feasibility files

NCHS created the 1999–2012 

NHIS–HUD public-use feasibility file 

and the 1999–2012 NHANES–HUD 

feasibility file, which can be downloaded 

directly from the NCHS website and 

merged with public-use NHIS and 

NHANES data, respectively. 

The feasibility files contain data on 

survey participants’ linkage eligibility 

status for the NCHS–HUD linkage, 

final match status, and whether the 

survey participant ever participated in 

HCV, MF, or PH programs. A survey 

participant is classified as “ever receiving 

HUD housing assistance” if the survey 

participant was linkage-eligible and 

had at least one transaction in the HUD 

administrative database during the 

linked NCHS–HUD administrative time 

period. Also provided are three variables 

representing ever participation in HCV, 

MF, or PH programs during the linked 

NCHS–HUD administrative time period. 

Program participation is not mutually 

exclusive across the administrative 

period. For example, a person may 

receive assistance as an MF program 

recipient and then receive an HCV during 

the linked NCHS–HUD administrative 

period.

The feasibility files can be used to 

determine the maximum available sample 

size to assess the feasibility of conducting 

analyses using the linked NCHS–HUD 

data by allowing researchers who are 

developing NCHS RDC proposals 

to determine if sufficient numbers of 

individuals and sufficient degrees of 

freedom exist in the category of interest 
Page 6  Series 1, No. 60

among those that have been successfully 

linked to HUD administrative data. 

These publicly available files also make 

it possible to identify demographic 

and health status variables available in 

the corresponding survey public-use 

data through subdividing the survey 

sample, calculating estimates of numbers 

of people in categories of interest, 

and determining cell sizes by related 

categories. 

Note that the feasibility files do not 

contain data pertaining to the timing 

of HUD assistance or details about the 

housing unit; instead, they contain record 

status variables and record counts to 

assist researchers who are considering 

whether to initiate an RDC proposal. 

Researchers should be aware that all 

NCHS surveys linked to the HUD 

administrative data have complex survey 

designs. Therefore, considerations of 

sample size and statistical power should 

take into account the survey design to 

produce statistically reliable analyses (2,6).

NCHS–HUD restricted-use 

transaction file

The transaction file contains a record 

for each HUD administrative transaction 

of the linked 1999–2012 NHIS–HUD and 

NHANES–HUD participants, and may 

contain more than one record per person. 

The transaction file contains detailed 

member and household attributes that 

are contained in HUD administrative 

systems. Transactions for child 

participants that occurred after the child’s 

18th birthday were removed during 

postprocessing, per ERB guidance.

NCHS–HUD restricted-use 

episode files

To facilitate analyses using the 

linked files, episode files were created 

with a single record per person containing 

the start and end dates for each period 

of continuous enrollment, or episode. 

An episode is a single continuous period 

of enrollment in a HUD program and is 

characterized by a start date and an end 

date. A graphical depiction of an episode 

is presented in Figure 2.

Seven episode files contain start 

and end dates for participation episodes. 

One file is for all HUD programs overall, 

and six additional files are for HUD 

subprograms based on the transaction 

data and assumptions about reasonable 

intervals between transactions (Appendix 

Table I). Most HUD housing assistance 

recipients are required to recertify each 

year, and consequently, a transaction 

is expected each year. However, some 

HUD programs have longer intervals 

between recertifications. The episode 

files are useful primarily for longitudinal 

analysis related to the duration and 

timing of housing assistance episodes, 

and conditions or outcomes that may 

have pre-existed or occurred after such 

episodes.

Figure 2. Temporal alignment of National Center for Health Statistics surveys linked to U.S. Department of Housing and Urban Development 

administrative data files

 

NOTES: The figure shows three possible scenarios related to the temporal alignment of the linked survey and housing assistance data for three hypothetical survey participants (SPs). In each

timeline, the arrow represents the year of the National Center for Health Statistics (NCHS) survey, and the rectangular box represents the time period (episode) during which the SP

received housing assistance from the U.S. Department of Housing and Urban Development (HUD). SP1 received HUD assistance after his or her interview, SP2 received HUD

assistance before his or her interview, and SP3 received HUD assistance concurrent with his or her interview.

SOURCES: NCHS, National Health Interview Survey and National Health and Nutrition Examination Survey, 1999–2012, data linked to HUD administrative records, 1996–2014.
Series 1, No. 60  Page 7 

NCHS–HUD restricted-use 

concurrency file 

The NCHS–HUD concurrency file 

is a restricted-use file that contains a 

single record for each linked participant 

and summarizes information based on 

timing of housing assistance relative to 

the date of the NCHS survey interview 

or examination. This file includes all 

linked survey participants, whether 

they were classified as concurrent 

or nonconcurrent. A linked survey 

participant is classified as concurrent 

if he or she was administered their 

NCHS survey interview or examination 

between the start and end dates of a HUD 

assistance episode. A graphical depiction 

of a survey participant who concurrently 

received HUD assistance at the time of 

the survey (SP3) is provided in Figure 2. 

A nonconcurrent participant would have 

partaken in the NCHS survey at some 

point outside of their HUD assistance 

episode (SP1 and SP2 in Figure 2). 

The concurrency file enables 

researchers to determine whether linked 

survey participants concurrently received 

HUD housing assistance at the time of 

the NHIS or NHANES interview or 

NHANES examination. Several factors 

influence the temporal alignment of 

the survey and administrative data, 

including age of the survey participant, 

HUD program eligibility, discontinuous 

program coverage, and residential 

mobility of the survey participants. 

More information about the concurrency 

variables is provided in Appendix III.

For researchers interested in 

examining the timing of HUD assistance 

for nonconcurrent linked participants, the 

number of days between the interview 

date and the end date of their most recent 

HUD episode was calculated, as well as 

the number of days between the interview 

date and the start date of their next 

HUD episode. Although these variables 

cannot be accessed directly by the 

researcher, researchers can request their 

own categories in their RDC proposal, 

based on the number of days between 

the NCHS interview or examination and 

a HUD transaction. More information 

about these timing variables is provided 

in Appendix III.

Table 3 presents the number and 

percentage of NHIS and NHANES linked 

participants who received HUD housing 

assistance concurrently, within 1, 2, and 

3 years of their survey interview. Data 

are presented by survey year and age at 

the time of interview (0–17 years, 18–39, 

40–64, and 65 and over). 

NCHS–HUD restricted-use 

sample weights file

The weights file contains a record 

for each 1999–2012 NHIS and NHANES 

participant who was linkage-eligible, and 

contains five sample weights (sample 

adult weight, sample child weight, and 

person weight for NHIS, and interview 

weight and MEC weight for NHANES) 

that correspond to the survey and are 

adjusted for linkage eligibility. All 

linkage-ineligible survey participants 

are given a weight of zero. The linkage 

eligibility-adjusted sample weights were 

derived using a model-based calibration 

approach. 

The sample weights provided in the 

NCHS population health survey data 

files adjust for oversampling of specific 

subgroups and differential nonresponse. 

The sample weights are poststratified 

to annual population totals for specific 

population domains to provide nationally 

representative estimates (2,12–14). 

Previous research suggests that survey 

participants who provide sufficient PII 

for linkage are not a random sample 

of survey participants. For some 

characteristics, linkage-eligible survey 

participants may differ systematically 

from survey participants who are not 

linkage-eligible; failing to account for 

linkage eligibility when examining 

these differences may lead to biased 

results (15). Analyses using the linked 

NCHS–HUD data should include only 

linkage-eligible survey participants rather 

than the full survey sample, and NCHS 

recommends using sample weights that 

are adjusted for linkage eligibility. 

To adjust for the potential bias that 

may result from differences between the 

linkage-eligible and linkage-ineligible 

populations, the linked NCHS–HUD 

data contain linkage-eligibility adjusted 

weights. A model-based calibration 

approach developed within the 

SUDAAN software package (Procedure 

WTADJUST or WTADJX) (16) was 

used to adjust the statistical weights for 

nonresponse with auxiliary information, 

specifically age, race and ethnicity, and 

sex. NCHS provides adjusted sample 

weights in a weights file based on this 

approach to account for differences 

in characteristics among linkageeligible and linkage-ineligible survey 

participants. Because inferences may 

depend on the approach used to adjust 

sample weights—within SUDAAN’s 

WTADJUST or using a different 

calibration approach—researchers 

are advised to seek assistance from a 

mathematical statistician for guidance on 

their particular project. Note that other 

approaches to calculating weights or 

handling possible linkage-eligibility bias 

with other statistical software packages 

can be used. More information about the 

eligibility-adjusted survey weights can be 

found in the Analytic Guidelines (7).

Access to Linked NCHS–

HUD Data Files 

Due to confidentiality requirements, 

NCHS restricts the availability of linked 

NCHS–HUD data files to researchers 

who have approved research proposals 

through NCHS RDC, with the exception 

of the NCHS–HUD feasibility files 

(available from: https://www.cdc.gov/

nchs/data-linkage/hud-feasibility.htm). 

More information regarding RDC and 

instructions for submitting an RDC 

proposal are available from: 

https://www.cdc.gov/rdc/.

Analytic 

Considerations

This section highlights general 

considerations and guidelines for analysis 

when using the linked data files; more 

detailed information can be found in 

the Analytic Guidelines (7). These 

general considerations do not replace 

the guidance for analyzing data from 

NHIS and NHANES. NCHS encourages 

researchers who discover new analytic 

issues during the course of their analysis 
Page 8  Series 1, No. 60

of the linked data to report them to 

the NCHS Data Linkage Program via 

datalinkage@cdc.gov.

As part of a researcher’s proposal 

to RDC, restricted variables from NCHS 

surveys and variables from the HUD files 

need to be specifically requested within 

the same proposal. For more information 

about restricted-use NCHS survey 

data, visit: https://www.cdc.gov/rdc/

b1datatype/dt122.htm. In the proposal, 

the researcher provides a file containing 

variables from the public-use NCHS 

survey data to RDC for merging with the 

requested restricted variables from NCHS 

surveys and the linked NCHS–HUD file 

variables. An RDC staff member verifies 

the full list of variables (restricted and 

public-use) and consults with the data 

divisions at NCHS that are responsible 

for producing the files, as well as with 

the NCHS confidentiality office to ensure 

that no potential disclosure risk of survey 

participants exists. A description of 

selected variables that may be useful in 

analyses of the linked NCHS–HUD data 

files is included in Appendix III.

Sample Weights

All proposals to use the linked data 

should request the correct sample weight 

to be used. The weights file contains a 

single record for all survey participants of 

1999–2012 NHIS and NHANES, as well 

as adjusted sample weights from NHIS 

(person weight, sample adult weight, 

and sample child weight) and NHANES 

(interview weight and MEC weight). See 

the Data Dictionary for more information 

about these variables (11).

Analyses Using Linked 

NCHS–HUD Data

NCHS recommends that researchers 

using the linked NCHS–HUD data 

combine survey years to increase sample 

size, if needed. Consult the analytic 

guidelines for NHANES (6,17) and NHIS 

(18,19) for instructions on combining 

years. Even though the survey periods for 

the linked 1999–2012 NHIS–HUD and 

NHANES–HUD data files overlap, data 

from the two surveys should be analyzed 

separately. 

Careful consideration is needed when 

examining characteristics among NCHS–

HUD linked participants and defining an 

analytic sample of linked participants. 

Although some characteristics (e.g., sex 

or race and ethnicity) are not likely to 

change over time or be associated with 

receipt of HUD housing assistance, 

other characteristics (e.g., type of health 

insurance coverage or poverty status) 

may differ because these characteristics 

are associated with receipt of HUD 

housing assistance. As a result, survey 

participants who were linked at any time 

during the administrative period and 

those who were receiving HUD housing 

assistance at the time of their survey 

interview or examination may differ for 

several characteristics.

When combining years of survey 

data, NCHS recommends that researchers 

assess the assumption of no trend in 

the estimates of the research variables 

of interest over the time periods being 

combined, including trends in the receipt 

of housing assistance, and changes in the 

quality of the HUD administrative data 

that may affect their study results.

Descriptive Analyses 

of Linked NHIS–HUD 

and NHANES–HUD 

Participants

The linked NCHS–HUD data 

allow for many different analyses, 

but note that the population of linked 

survey participants may differ from 

both their respective survey populations 

as well as the overall population of 

HUD housing assistance recipients. 

Survey participants who were linked 

to the HUD administrative data may 

not be representative of the larger 

survey populations and differ by certain 

characteristics, such as poverty status, 

that would make them more likely to 

receive HUD housing assistance. This 

section provides a brief descriptive 

analysis of the linked NHIS–HUD and 

NHANES–HUD participants and their 

similarities to and differences from 

their respective survey populations. A 

comparison between the population of 

linked survey participants and the overall 

population of HUD housing assistance 

recipients is presented in Appendix IV.

Descriptive statistics for 2008–2012 

NHIS and 2009–2012 NHANES 

participants and linked survey 

participants from those same surveys are 

presented in Tables 4–7. Children (aged 

0–17 years) and adults (aged 18 and 

over) are presented separately. Summary 

statistics for the linked NHIS–HUD data 

are presented in Tables 4 and 5; linked 

NHANES–HUD summary statistics are 

shown in Tables 6 and 7. The sample 

weights used in preparing the summary 

statistics are those in the weights file 

and are adjusted for linkage eligibility 

as described previously. Researchers 

should be aware that applying different 

analytic approaches (i.e., variable 

parameterization and alternative 

approaches to weight adjustment) may 

result in findings different from those 

presented below. 

The following criteria were used 

to assess similarities and differences 

in the selected sociodemographic and 

health characteristics between linked 

participants and the survey population:

1. If the percentage for each 

category (e.g., male or female) of 

a characteristic (e.g., sex) is equal 

for both linked participants and the 

survey population, it is described as 

being the same. 

2. If the relative difference between 

the linked sample and the survey 

population, defined as:

 | Xpopulation – Xlinked | / Xpopulation

is between 0.0 and 0.1 for all 

categories of the characteristic, the 

linked sample is described as being 

“consistent or similar” to the survey 

population with respect to that 

characteristic. 

3. If the relative difference between 

the linked sample and the survey 

population for at least one category 

of the characteristic is 0.1 or greater, 

the linked sample is described 

as being “different (higher/more 

or lower/less)” than the survey 

population with respect to that 

characteristic.
Series 1, No. 60  Page 9 

 Because the two populations (linked 

participants and the survey population) 

were not statistically independent and 

measures of correlation between the two 

populations were not readily available, 

comparisons were not statistically tested.

Descriptive statistics for 2008–2012 

NHIS child participants and linked child 

survey participants are presented in 

Table 4. The percentages of the linked 

child survey participants that were 

male (49.6%) and female (50.4%) were 

similar to the percentages among the 

NHIS population aged 0–17 years (males 

51.1%, females 48.9%). However, the 

distributions of age, race and ethnicity, 

poverty status, health status, and health 

insurance coverage differed between 

the two populations. Compared to the 

population of NHIS child participants, 

more of the linked child survey 

participants were aged 6–11 years (38.5% 

compared to 32.9%) and non-Hispanic 

black (47.7% compared to 15.3%), and 

had family incomes that were below the 

poverty threshold (59.2% compared to 

21.5%). The percentage of children with 

fair or poor health was higher among the 

linked child survey participants (5.0%) 

than among NHIS child participants 

(1.9%), and more linked child survey 

participants had public insurance (67.7%) 

compared to NHIS child participants 

(26.6%).

Descriptive statistics for 2008–2012 

NHIS adult participants and linked adult 

survey participants are presented in Table 5.

The distributions of sex, age, race and 

ethnicity, poverty status, health status, 

and health insurance coverage among 

linked adult survey participants differed 

between the two populations. Compared 

to NHIS adult participants, more linked 

adult survey participants were female 

(69.5% compared to 51.7%), aged 

18–39 (54.9% compared to 39.1%), and 

non-Hispanic black (37.1% compared 

to 11.9%), and had family incomes that 

were below the poverty threshold (48.0% 

compared to 12.8%), fair or poor health 

(29.1% compared to 12.7%), and public 

insurance (47.7% compared to 15.3%).

Descriptive statistics for 2009–2012 

NHANES child participants and linked 

child survey participants are presented 

in Table 6. The percentages of linked 

child survey participants that were male 

(49.1%) and female (50.9%) were similar 

to the percentages among the NHANES 

population aged 0–17 years (males 

50.7%, females 49.3%). However, the 

distributions of age, race and ethnicity, 

poverty status, health status, and health 

insurance coverage differed between the 

two populations. More of the linked child 

survey participants were aged 12–17 

years (40.6% compared to 34.5%) and 

non-Hispanic black (45.8% compared 

to 14.2%), and had family incomes 

that were below the poverty threshold 

(61.0% compared to 23.5%). Compared 

to NHANES child participants, linked 

child survey participants had a higher 

percentage with fair or poor health 

(7.1% compared to 4.3%) and a lower 

percentage with no health insurance 

coverage (5.5% compared to 8.0%).

Descriptive statistics for 2009–

2012 NHANES adult participants and 

linked adult survey participants aged 

18 and over are presented in Table 7. 

The distributions of sex, age, race and 

ethnicity, poverty status, health status, 

and health insurance coverage differed 

between the two populations. Compared 

to NHANES adult participants, more 

linked adult survey participants were 

female (66.7% compared to 51.7%), aged 

18–39 (52.8% compared to 38.7%), and 

non-Hispanic black (35.6% compared 

to 11.6%), and had family incomes that 

were below the poverty guideline (47.1% 

compared to 15.8%), had fair or poor 

health (33.5% compared to 17.2%), and 

were uninsured (26.1% compared to 

20.3%).

These results may assist researchers 

in understanding how linked survey 

participants differ from the overall 

survey sample and demonstrate that 

inferences about research findings 

based on the linked sample may not be 

generalizable to the national population. 

Additionally, the linked data are not 

intended to reflect the entire population 

of HUD housing assistance recipients. 

The linked participants represent 

the survey participants that received 

federal housing assistance at some 

time point in the linked NCHS–HUD 

administrative period. This may not 

be the same as the entire population 

of HUD housing assistance recipients 

because of the sample design of the 

surveys, which include only the civilian 

noninstitutionalized U.S. population. In 

Appendix IV, characteristics of the linked 

sample and the entire HUD-assisted 

population are presented to illustrate 

similarities and differences between 

linked survey participants and the entire 

population receiving HUD assistance. 

Conclusion 

The linked NCHS–HUD data are 

the first NCHS linked data product 

combining health and housing assistance 

data and stem from an interagency 

collaboration between NCHS and HUD. 

These data provide information about 

health characteristics of persons who 

received HUD housing assistance during 

the 1999–2014 HUD administrative 

period, including those receiving HUD 

housing assistance at the time of their 

survey interview and/or examination. 

While the distribution of various 

characteristics (such as sex, or race and 

ethnicity) remained consistent between 

individuals who had been linked and the 

overall sample, several characteristics 

appear to differ (such as poverty status). 

These differences in characteristics, as 

well as changes in the data or receipt of 

assistance over time, may impact findings 

from analyses of the linked NCHS–HUD 

data. 

The linkage of health data from 

NHIS and NHANES to housing 

assistance data from the HUD 

administrative records enhances the 

utility of these population health surveys 

as well as the HUD administrative data. 

The NCHS–HUD linkage provides 

a unique opportunity to examine the 

relationship between receipt of assisted 

housing and various health-related 

outcomes, such as access to health care 

and utilization of health services, general 

health status, health characteristics, and 

health behaviors.
Page 10  Series 1, No. 60

Published Research 

Papers Using NCHS 

Surveys Linked to 

HUD Data

● Ahrens KA, Haley BA, Rossen 

LM, Lloyd PC, Aoki Y. Housing 

assistance and blood lead levels: 

Children in the United States, 

2005–2012. Am J Public Health 

106(11):2049–56. 2016. 

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MD. 2013.

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linked data: Analytic considerations 

and guidelines. Hyattsville, MD: 

National Center for Health Statistics. 

2016. Available from: https://www.

cdc.gov/nchs/data/datalinkage/nchs_

hud_analytic_considerations.pdf.

8. Miller DM, Gindi RM, Parker JD. 

Trends in record linkage refusal 

rates: Characteristics of National 

Health Interview Survey participants 

who refuse record linkage. Presented 

at: Joint Statistical Meeting. Miami 

Beach, FL: American Statistical 

Association. 2011.

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in a handshake? The role of SSN 

in NDI record linkage. Presented 

at: Joint Statistical Meeting. San 

Francisco, CA: American Statistical 

Association. 2003. 

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and data structures. 2009. Available 

from: https://www.nist.gov/dads/. 

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NCHS–HUD linked data: Data 

dictionary. 2016.

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and estimation for the National 

Health Interview Survey, 1995–

2004. National Center for Health 

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Dohrmann SM, et al. The National 

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MD. Adjusting sample weights for 

linkage-eligibility using SUDAAN. 

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Health Statistics. 2013.

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language manual, vol 1–2 

(Release 11). 2012.

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Variance estimation guidance, NHIS 

2006–2015. Hyattsville, MD. 2016.

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analytic issues in the 1997–2005 

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Table 1. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: National Health Interview Survey, 

Survey year and 

age (years) at 

NHIS interview

 All NHIS participants Sample Adult S

 Total

sample 

 Eligible for linkage Linked to HUD 

 Total 

sample 

Eligible for linkage Linked to HUD

 Total 

sample 

Eligible for 

n

Percent of 

total n

Percent of 

eligible n 

Percent of 

total n

Percent of 

eligible n

1999–2012

Total . . . . . . . . . . . . . . . . . . . 1,291,224 316,102 24.48 27,555 8.72 413,027 205,905 49.85 18,610 9.04 166,212 41,599 

1999

Total . . . . . . . . . . . . . . . . . . . 97,059 36,822 37.94 2,673 7.26 30,801 17,115 55.57 1,411 8.24 12,910 3,698 

0–17 . . . . . . . . . . . . . . . . . 27,271 7,050 25.85 698 9.90 ... ... ... ... ... 12,910 3,698 18–39 . . . . . . . . . . . . . . . . 30,183 11,709 38.79 905 7.73 12,544 6,716 53.54 603 8.98 ... ... 

40–64 . . . . . . . . . . . . . . . . 28,605 12,387 43.30 671 5.42 12,255 6,750 55.08 465 6.89 ... ... 65 and over. . . . . . . . . . . . 11,000 5,676 51.60 399 7.03 6,002 3,649 60.80 343 9.40 ... ... 

2000

Total . . . . . . . . . . . . . . . . . . . 100,618 35,318 35.10 2,815 7.97 32,374 16,605 51.29 1,433 8.63 13,376 3,504 

0–17 . . . . . . . . . . . . . . . . . 28,495 6,755 23.71 829 12.27 ... ... ... ... ... 13,376 3,504 

18–39 . . . . . . . . . . . . . . . . 31,153 11,263 36.15 892 7.92 13,283 6,512 49.03 609 9.35 ... ... 

40–64 . . . . . . . . . . . . . . . . 29,764 11,903 39.99 680 5.71 12,911 6,609 51.19 479 7.25 ... ... 

65 and over. . . . . . . . . . . . 11,206 5,397 48.16 414 7.67 6,180 3,484 56.38 345 9.90 ... ... 

2001

Total . . . . . . . . . . . . . . . . . . . 100,760 35,397 35.13 2,701 7.63 33,326 16,997 51.00 1,384 8.14 13,579 3,551 

0–17 . . . . . . . . . . . . . . . . . 28,572 6,763 23.67 807 11.93 ... ... ... ... ... 13,579 3,551 

18–39 . . . . . . . . . . . . . . . . 30,941 11,131 35.97 912 8.19 13,555 6,590 48.62 612 9.29 ... ... 

40–64 . . . . . . . . . . . . . . . . 30,230 12,191 40.33 612 5.02 13,619 6,939 50.95 461 6.64 ... ... 

65 and over. . . . . . . . . . . . 11,017 5,312 48.22 370 6.97 6,152 3,468 56.37 311 8.97 ... ... 

2002

Total . . . . . . . . . . . . . . . . . . . 93,386 16,681 17.86 1,385 8.30 31,044 11,353 36.57 1,119 9.86 12,524 ... 

0–17 . . . . . . . . . . . . . . . . . 26,191 ... ... ... ... ... ... ... ... ... 12,524 ... 18–39 . . . . . . . . . . . . . . . . 28,298 6,148 21.73 600 9.76 12,467 4,219 33.84 455 10.78 ... ... 

40–64 . . . . . . . . . . . . . . . . 28,312 7,134 25.20 472 6.62 12,717 4,629 36.40 373 8.06 ... ... 

65 and over. . . . . . . . . . . . 10,585 3,399 32.11 313 9.21 5,860 2,505 42.75 291 11.62 ... ... 

2003

Total . . . . . . . . . . . . . . . . . . . 92,148 14,805 16.07 1,305 8.81 30,852 10,223 33.14 1,062 10.39 12,249 ... 

0–17 . . . . . . . . . . . . . . . . . 25,537 ... ... ... ... ... ... ... ... ... 12,249 ... 

18–39 . . . . . . . . . . . . . . . . 27,809 5,383 19.36 568 10.55 12,154 3,782 31.12 446 11.79 ... ... 

40–64 . . . . . . . . . . . . . . . . 28,529 6,416 22.49 474 7.39 12,939 4,204 32.49 384 9.13 ... ... 

65 and over. . . . . . . . . . . . 10,273 3,006 29.26 263 8.75 5,759 2,237 38.84 232 10.37 ... ... 

2004

Total . . . . . . . . . . . . . . . . . . . 94,460 21,744 23.02 1,790 8.23 31,326 13,428 42.87 1,170 8.71 12,424 3,170 

0–17 . . . . . . . . . . . . . . . . . 26,161 3,175 12.14 384 12.09 ... ... ... ... ... 12,424 3,170 18–39 . . . . . . . . . . . . . . . . 28,015 6,896 24.62 648 9.40 12,052 5,080 42.15 517 10.18 ... ... 

40–64 . . . . . . . . . . . . . . . . 29,526 7,984 27.04 463 5.80 13,255 5,503 41.52 384 6.98 ... ... 

65 and over. . . . . . . . . . . . 10,758 3,689 34.29 295 8.00 6,019 2,845 47.27 269 9.46 ... ... 

See footnotes at end of table.
Table 1. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: National Health Interview Survey, 

Survey year and age (years) at NHIS interview All NHIS participants Sample Adult S

 Total sample Eligible for linkage Linked to HUD Total sample Eligible for linkage Linked to HUD Total sample Eligible for 

n Percent of total n Percent of eligible n Percent of total n Percent of eligible n 

2005 Total . . . . . . . . . . . . . . . . . . . 98,649 18,765 19.02 1,608 8.57 31,428 11,727 37.31 1,036 8.83 12,523 2,658 

0–17 . . . . . . . . . . . . . . . . . 26,814 2,660 9.92 332 12.48 ... ... ... ... ... 12,523 2,658 18–39 . . . . . . . . . . . . . . . . 28,982 5,778 19.94 619 10.71 11,810 4,260 36.07 488 11.46 ... ... 40–64 . . . . . . . . . . . . . . . . 31,623 7,137 22.57 442 6.19 13,540 4,959 36.62 351 7.08 ... ... 65 and over . . . . . . . . . . . 11,230 3,190 28.41 215 6.74 6,078 2,508 41.26 197 7.85 ... ... 

2006

Total . . . . . . . . . . . . . . . . . . . 75,716 13,319 17.59 1,370 10.29 24,275 8,418 34.68 919 10.92 9,837 1,806 

0–17 . . . . . . . . . . . . . . . . . 20,903 1,806 8.64 249 13.79 ... ... ... ... ... 9,837 1,806 

18–39 . . . . . . . . . . . . . . . . 22,578 4,322 19.14 535 12.38 9,418 3,235 34.35 440 13.60 ... ... 

40–64 . . . . . . . . . . . . . . . . 23,845 4,922 20.64 387 7.86 10,210 3,401 33.31 300 8.82 ... ... 65 and over . . . . . . . . . . . 8,390 2,269 27.04 199 8.77 4,647 1,782 38.35 179 10.04 ... ... 

2007

Total . . . . . . . . . . . . . . . . . . . 75,764 14,247 18.8 1,338 9.39 23,393 11,643 49.77 1,012 8.69 9,417 2,604 

0–17 . . . . . . . . . . . . . . . . . 20,719 2,604 12.57 326 12.52 ... ... ... ... ... 9,417 2,604 

18–39 . . . . . . . . . . . . . . . . 22,598 4,358 19.28 484 11.11 8,864 4,358 49.17 484 11.11 ... ... 

40–64 . . . . . . . . . . . . . . . . 24,008 5,029 20.95 349 6.94 9,946 5,029 50.56 349 6.94 ... ... 

65 and over . . . . . . . . . . . 8,439 2,256 26.73 179 7.93 4,583 2,256 49.23 179 7.93 ... ... 

2008

Total . . . . . . . . . . . . . . . . . . . 74,236 15,268 20.57 1,462 9.58 21,781 12,438 57.10 1,109 8.92 8,815 2,830 

0–17 . . . . . . . . . . . . . . . . . 19,914 2,830 14.21 353 12.47 ... ... ... ... ... 8,815 2,830 18–39 . . . . . . . . . . . . . . . . 22,116 4,574 20.68 538 11.76 8,067 4,574 56.70 538 11.76 ... ... 40–64 . . . . . . . . . . . . . . . . 23,728 5,380 22.67 374 6.95 9,270 5,380 58.04 374 6.95 ... ... 65 and over . . . . . . . . . . . 8,478 2,484 29.3 197 7.93 4,444 2,484 55.90 197 7.93 ... ... 

2009

Total . . . . . . . . . . . . . . . . . . . 88,446 21,580 24.4 2,208 10.23 27,731 17,413 62.79 1,653 9.49 11,156 4,167 

0–17 . . . . . . . . . . . . . . . . . 23,830 4,167 17.49 555 13.32 ... ... ... ... ... 11,156 4,167 

18–39 . . . . . . . . . . . . . . . . 25,952 6,306 24.3 794 12.59 10,277 6,306 61.36 794 12.59 ... ... 

40–64 . . . . . . . . . . . . . . . . 28,546 7,608 26.65 592 7.78 11,961 7,608 63.61 592 7.78 ... ... 

65 and over . . . . . . . . . . . 10,118 3,499 34.58 267 7.63 5,493 3,499 63.70 267 7.63 ... ... 

2010

Total . . . . . . . . . . . . . . . . . . . 89,976 20,139 22.38 1,917 9.52 27,157 16,073 59.19 1,447 9.00 11,277 4,066 

0–17 . . . . . . . . . . . . . . . . . 24,057 4,066 16.9 470 11.56 ... ... ... ... ... 11,277 4,066 

18–39 . . . . . . . . . . . . . . . . 26,788 5,970 22.29 684 11.46 10,200 5,970 58.53 684 11.46 ... ... 

40–64 . . . . . . . . . . . . . . . . 28,691 6,912 24.09 515 7.45 11,507 6,912 60.07 515 7.45 ... ... 

65 and over. . . . . . . . . . . . 10,440 3,191 30.57 248 7.77 5,450 3,191 58.55 248 7.77 ... ... 

See footnotes at end of table.
Table 1. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: National Health Interview Survey, 

Survey year and 

age (years) at 

NHIS interview

 All NHIS participants Sample Adult S

 Total

sample 

 Eligible for linkage Linked to HUD 

 Total 

sample 

Eligible for linkage Linked to HUD

 Total 

sample 

Eligible for 

n 

Percent of 

total n

Percent of 

eligible n

Percent of 

total n

Percent of 

eligible n

2011

Total . . . . . . . . . . . . . . . . . . . 101,875 25,786 25.31 2,378 9.22 33,014 21,055 63.78 1,820 8.64 12,850 4,731 

0–17 . . . . . . . . . . . . . . . . . 26,802 4,731 17.65 558 11.79 ... ... ... ... ... 12,850 4,731 18–39 . . . . . . . . . . . . . . . . 29,970 7,704 25.71 901 11.70 12,191 7,704 63.19 901 11.70 ... ... 

40–64 . . . . . . . . . . . . . . . . 32,586 8,870 27.22 608 6.85 13,921 8,870 63.72 608 6.85 ... ... 65 and over . . . . . . . . . . . 12,517 4,481 35.80 311 6.94 6,902 4,481 64.92 311 6.94 ... ... 

2012

Total . . . . . . . . . . . . . . . . . . . 108,131 26,231 24.26 2,605 9.93 34,525 21,417 62.03 2,035 9.50 13,275 4,814 

0–17 . . . . . . . . . . . . . . . . . 28,016 4,814 17.18 570 11.84 ... ... ... ... ... 13,275 4,814 

18–39 . . . . . . . . . . . . . . . . 31,184 7,555 24.23 972 12.87 12,434 7,555 60.76 972 12.87 ... ... 

40–64 . . . . . . . . . . . . . . . . 35,361 9,218 26.07 700 7.59 14,709 9,218 62.67 700 7.59 ... ... 65 and over. . . . . . . . . . . . 13,570 4,644 34.22 363 7.82 7,382 4,644 62.91 363 7.82 ... ... 

... Category not applicable.NOTE: HUD is U.S. Department of Housing and Urban Development, and NHIS is National Health Interview Survey.SOURCES: NCHS, 1999–2012 NHIS data linked to 1999–2014 HUD administrative records.
Page 14  Series 1, No. 60

Table 2. Sample size and percentage of survey participants linked to HUD data, by survey year and age at interview: National Health and 

Nutrition Examination Survey, 1999–2012

Survey year and 

age (years) at 

NHANES interview

All NHANES participants MEC participants

 Total

sample 

Eligible for linkage Linked to HUD

 Total

sample 

Eligible for linkage Linked to HUD

n 

Percent of 

total n

Percent of 

eligible n

Percent of 

total n

Percent of 

eligible

1999–2012

Total . . . . . . . . . . . . . . . . . . . . . . . 71,916 50,559 70.30 6,532 12.92 75,127 48,769 64.92 6,354 13.03

1999–2000

Total . . . . . . . . . . . . . . . . . . . . . . . 9,965 7,235 72.60 882 12.19 10,648 6,843 64.27 850 12.42

0–17 . . . . . . . . . . . . . . . . . . . . . 4,517 2,933 64.93 452 15.41 4,728 2,839 60.05 443 15.60

18–39 . . . . . . . . . . . . . . . . . . . . 2,263 1,714 75.74 188 10.97 2,425 1,607 66.27 183 11.39

40–64 . . . . . . . . . . . . . . . . . . . . 1,793 1,475 82.26 127 8.61 1,907 1,400 73.41 122 8.71

65 and over. . . . . . . . . . . . . . . . 1,392 1,113 79.96 115 10.33 1,588 997 62.78 102 10.23

2001–2002

Total . . . . . . . . . . . . . . . . . . . . . . . 11,039 8,715 78.95 1,199 13.76 11,601 8,346 71.94 1,160 13.90

0–17 . . . . . . . . . . . . . . . . . . . . . 5,046 3,709 73.50 711 19.17 5,207 3,626 69.64 700 19.31

18–39 . . . . . . . . . . . . . . . . . . . . 2,507 2,002 79.86 266 13.29 2,606 1,929 74.02 261 13.53

40–64 . . . . . . . . . . . . . . . . . . . . 2,023 1,753 86.65 108 6.16 2,104 1,691 80.37 104 6.15

65 and over. . . . . . . . . . . . . . . . 1,463 1,251 85.51 114 9.11 1,684 1,100 65.32 95 8.64

2003–2004

Total . . . . . . . . . . . . . . . . . . . . . . . 10,122 8,084 79.87 1,075 13.30 10,601 7,764 73.24 1,045 13.46

0–17 . . . . . . . . . . . . . . . . . . . . . 4,502 3,265 72.52 600 18.38 4,664 3,176 68.10 587 18.48

18–39 . . . . . . . . . . . . . . . . . . . . 2,321 1,930 83.15 258 13.37 2,425 1,856 76.54 255 13.74

40–64 . . . . . . . . . . . . . . . . . . . . 1,805 1,573 87.15 126 8.01 1,896 1,501 79.17 123 8.19

65 and over. . . . . . . . . . . . . . . . 1,494 1,316 88.09 91 6.91 1,616 1,231 76.18 80 6.50

2005–2006

Total . . . . . . . . . . . . . . . . . . . . . . . 10,348 7,298 70.53 911 12.48 10,746 7,073 65.82 888 12.55

0–17 . . . . . . . . . . . . . . . . . . . . . 4,785 3,079 64.35 522 16.95 4,954 3,001 60.58 510 16.99

18–39 . . . . . . . . . . . . . . . . . . . . 2,507 1,816 72.44 211 11.62 2,614 1,748 66.87 205 11.73

40–64 . . . . . . . . . . . . . . . . . . . . 1,867 1,448 77.56 111 7.67 1,925 1,413 73.40 109 7.71

65 and over. . . . . . . . . . . . . . . . 1,189 955 80.32 67 7.02 1,253 911 72.71 64 7.03

2007–2008

Total . . . . . . . . . . . . . . . . . . . . . . . 10,149 6,724 66.25 873 12.98 10,536 6,543 62.10 858 13.11

0–17 . . . . . . . . . . . . . . . . . . . . . 3,921 2,186 55.75 427 19.53 4,075 2,127 52.20 417 19.61

18–39 . . . . . . . . . . . . . . . . . . . . 2,203 1,537 69.77 217 14.12 2,274 1,501 66.01 215 14.32

40–64 . . . . . . . . . . . . . . . . . . . . 2,469 1,823 73.84 157 8.61 2,543 1,784 70.15 156 8.74

65 and over. . . . . . . . . . . . . . . . 1,556 1,178 75.71 72 6.11 1,644 1,131 68.80 70 6.19

2009–2010

Total . . . . . . . . . . . . . . . . . . . . . . . 10,537 6,607 62.70 754 11.41 10,821 6,482 59.90 738 11.39

0–17 . . . . . . . . . . . . . . . . . . . . . 4,010 2,084 51.97 299 14.35 4,127 2,041 49.45 293 14.36

18–39 . . . . . . . . . . . . . . . . . . . . 2,392 1,587 66.35 219 13.80 2,450 1,560 63.67 217 13.91

40–64 . . . . . . . . . . . . . . . . . . . . 2,612 1,808 69.22 153 8.46 2,658 1,783 67.08 149 8.36

65 and over. . . . . . . . . . . . . . . . 1,523 1,128 74.06 83 7.36 1,586 1,098 69.23 79 7.19

2011–2012

Total . . . . . . . . . . . . . . . . . . . . . . . 9,756 5,896 60.43 838 14.21 10,174 5,718 56.20 815 14.25

0–17 . . . . . . . . . . . . . . . . . . . . . 3,892 1,904 48.92 339 17.80 4,061 1,849 45.53 332 17.96

18–39 . . . . . . . . . . . . . . . . . . . . 2,261 1,468 64.93 229 15.60 2,348 1,420 60.48 222 15.63

40–64 . . . . . . . . . . . . . . . . . . . . 2,353 1,601 68.04 158 9.87 2,431 1,568 64.50 156 9.95

65 and over. . . . . . . . . . . . . . . . 1,250 923 73.84 112 12.13 1,334 881 66.04 105 11.92

NOTE: HUD is U.S. Department of Housing and Urban Development, NHANES is National Health and Nutrition Examination Survey, and MEC is mobile examination center.

SOURCES: NCHS, 1999–2012 NHANES data linked to 1996–2014 HUD administrative records.
Series 1, No. 60  Page 15 

Table 3. Linked NCHS–HUD file sample size and percentage of linked survey participants with concurrent HUD enrollment within 1, 2, and

3 years of survey interview, by survey and age at interview

Survey year and 

age (years) at 

NCHS interview

 Linked 

respondents 

 Concurrently 

linked 

 Within 1 year 

of interview 

 Within 2 years 

of interview 

 Within 3 years 

of interview 

n n

Percent of 

all linked n

Percent of 

all linked n

Percent of 

all linked n

Percent of 

all linked

NHIS

1999–2012 total . . . . . . . . . . . . . . . . 27,555 11,060 40.1 16,076 58.3 18,666 67.7 20,394 74.0

1999 total . . . . . . . . . . . . . . . . . . . . . 2,673 234 08.8 1,106 41.4 1,638 61.3 1,805 67.5

0–17 . . . . . . . . . . . . . . . . . . . . . . . 698 48 06.9 316 45.3 488 69.9 520 74.5

18–39 . . . . . . . . . . . . . . . . . . . . . . 905 56 06.2 327 36.1 507 56.0 584 64.5

40–64 . . . . . . . . . . . . . . . . . . . . . . 671 56 08.4 241 35.9 355 52.9 390 58.1

65 and over. . . . . . . . . . . . . . . . . . 399 74 18.6 222 55.6 288 72.2 311 77.9

2000 total . . . . . . . . . . . . . . . . . . . . . 2,815 735 26.1 1,557 55.3 1,783 63.3 1,998 71.0

0–17 . . . . . . . . . . . . . . . . . . . . . . . 829 226 27.3 496 59.8 571 68.9 637 76.8

18–39 . . . . . . . . . . . . . . . . . . . . . . 892 192 21.5 455 51.0 540 60.5 621 69.6

40–64 . . . . . . . . . . . . . . . . . . . . . . 680 160 23.5 331 48.7 369 54.3 416 61.2

65 and over. . . . . . . . . . . . . . . . . . 414 157 37.9 275 66.4 303 73.2 324 78.3

2001 total . . . . . . . . . . . . . . . . . . . . . 2,701 806 29.8 1,517 56.2 1,777 65.8 1,933 71.6

0–17 . . . . . . . . . . . . . . . . . . . . . . . 807 234 29.0 464 57.5 565 70.0 612 75.8

18–39 . . . . . . . . . . . . . . . . . . . . . . 912 229 25.1 478 52.4 565 62.0 622 68.2

40–64 . . . . . . . . . . . . . . . . . . . . . . 612 195 31.9 320 52.3 366 59.8 399 65.2

65 and over. . . . . . . . . . . . . . . . . . 370 148 40.0 255 68.9 281 76.0 300 81.1

2002 total . . . . . . . . . . . . . . . . . . . . . 1,385 483 34.9 802 57.9 959 69.2 1,046 75.5

0–17 . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... ... ... ... ... 

18–39 . . . . . . . . . . . . . . . . . . . . . . 600 176 29.3 320 53.3 410 68.3 457 76.2

40–64 . . . . . . . . . . . . . . . . . . . . . . 472 167 35.4 277 58.7 317 67.2 343 72.7

65 and over. . . . . . . . . . . . . . . . . . 313 140 44.7 205 65.5 232 74.1 246 78.6

2003 total . . . . . . . . . . . . . . . . . . . . . 1,305 537 41.2 800 61.3 929 71.2 1,023 78.4

0–17 . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... ... ... ... ... 

18–39 . . . . . . . . . . . . . . . . . . . . . . 568 188 33.1 299 52.6 367 64.6 431 75.9

40–64 . . . . . . . . . . . . . . . . . . . . . . 474 218 46.0 304 64.1 344 72.6 367 77.4

65 and over. . . . . . . . . . . . . . . . . . 263 131 49.8 197 74.9 218 82.9 225 85.6

2004 total . . . . . . . . . . . . . . . . . . . . . 1,790 771 43.1 1,091 61.0 1,279 71.5 1,407 78.6

0–17 . . . . . . . . . . . . . . . . . . . . . . . 384 162 42.2 242 63.0 289 75.3 325 84.6

18–39 . . . . . . . . . . . . . . . . . . . . . . 648 230 35.5 359 55.4 430 66.4 489 75.5

40–64 . . . . . . . . . . . . . . . . . . . . . . 463 207 44.7 273 59.0 319 68.9 345 74.5

65 and over. . . . . . . . . . . . . . . . . . 295 172 58.3 217 73.6 241 81.7 248 84.1

2005 total . . . . . . . . . . . . . . . . . . . . . 1,608 688 42.8 951 59.1 1,107 68.8 1,227 76.3

0–17 . . . . . . . . . . . . . . . . . . . . . . . 332 142 42.8 209 63.0 246 74.1 272 81.9

18–39 . . . . . . . . . . . . . . . . . . . . . . 619 229 37.0 331 53.5 394 63.7 446 72.1

40–64 . . . . . . . . . . . . . . . . . . . . . . 442 182 41.2 250 56.6 291 65.8 318 72.0

65 and over. . . . . . . . . . . . . . . . . . 215 135 62.8 161 74.9 176 81.9 191 88.8

2006 total . . . . . . . . . . . . . . . . . . . . . 1,370 601 43.9 799 58.3 930 67.9 1,066 77.8

0–17 . . . . . . . . . . . . . . . . . . . . . . . 249 99 39.8 140 56.2 174 69.9 207 83.1

18–39 . . . . . . . . . . . . . . . . . . . . . . 535 197 36.8 283 52.9 327 61.1 383 71.6

40–64 . . . . . . . . . . . . . . . . . . . . . . 387 185 47.8 230 59.4 267 69.0 305 78.8

65 and over. . . . . . . . . . . . . . . . . . 199 120 60.3 146 73.4 162 81.4 171 85.9

2007 total . . . . . . . . . . . . . . . . . . . . . 1,338 667 49.9 822 61.4 953 71.2 1,048 78.3

0–17 . . . . . . . . . . . . . . . . . . . . . . . 326 164 50.3 211 64.7 248 76.1 269 82.5

18–39 . . . . . . . . . . . . . . . . . . . . . . 484 215 44.4 270 55.8 323 66.7 357 73.8

40–64 . . . . . . . . . . . . . . . . . . . . . . 349 168 48.1 206 59.0 234 67.1 261 74.8

65 and over. . . . . . . . . . . . . . . . . . 179 120 67.0 135 75.4 148 82.7 161 89.9

2008 total . . . . . . . . . . . . . . . . . . . . . 1,462 729 49.9 905 61.9 998 68.3 1,094 74.8

0–17 . . . . . . . . . . . . . . . . . . . . . . . 353 170 48.2 221 62.6 246 69.7 269 76.2

18–39 . . . . . . . . . . . . . . . . . . . . . . 538 212 39.4 279 51.9 320 59.5 370 68.8

40–64 . . . . . . . . . . . . . . . . . . . . . . 374 208 55.6 244 65.2 266 71.1 286 76.5

65 and over. . . . . . . . . . . . . . . . . . 197 139 70.6 161 81.7 166 84.3 169 85.8

2009 total . . . . . . . . . . . . . . . . . . . . . 2,208 1,161 52.6 1,389 62.9 1,566 70.9 1,690 76.5

0–17 . . . . . . . . . . . . . . . . . . . . . . . 555 283 51.0 358 64.5 413 74.4 448 80.7

18–39 . . . . . . . . . . . . . . . . . . . . . . 794 347 43.7 419 52.8 489 61.6 543 68.4

40–64 . . . . . . . . . . . . . . . . . . . . . . 592 337 56.9 391 66.1 431 72.8 457 77.2

65 and over. . . . . . . . . . . . . . . . . . 267 194 72.7 221 82.8 233 87.3 242 90.6

See footnotes at end of table.
Page 16  Series 1, No. 60

Table 3. Linked NCHS–HUD file sample size and percentage of linked survey participants with concurrent HUD enrollment within 1, 2, and

3 years of survey interview, by survey and age at interview—Con.

Survey year and 

age (years) at 

NCHS interview

 Linked 

respondents 

 Concurrently 

linked 

 Within 1 year 

of interview 

 Within 2 years

of interview 

 Within 3 years

of interview 

n n

Percent of

all linked n

Percent of

all linked n

Percent of all 

linked n

Percent of all 

linked

NHIS—Con.

2010 total . . . . . . . . . . . . . . . . . . . . . 1,917 974 50.8 1,198 62.5 1,337 69.7 1,447 75.5

0–17 . . . . . . . . . . . . . . . . . . . . . . . 470 215 45.7 283 60.2 329 70.0 365 77.7

18–39 . . . . . . . . . . . . . . . . . . . . . . 684 274 40.1 366 53.5 421 61.6 458 67.0

40–64 . . . . . . . . . . . . . . . . . . . . . . 515 294 57.1 343 66.6 370 71.8 395 76.7

65 and over. . . . . . . . . . . . . . . . . . 248 191 77.0 206 83.1 217 87.5 229 92.3

2011 total. . . . . . . . . . . . . . . . . . . . . . 2,378 1,231 51.8 1,481 62.3 1,623 68.3 1,731 72.8

0–17 . . . . . . . . . . . . . . . . . . . . . . . 558 266 47.7 351 62.9 394 70.6 423 75.8

18–39 . . . . . . . . . . . . . . . . . . . . . . 901 384 42.6 469 52.1 521 57.8 562 62.4

40–64 . . . . . . . . . . . . . . . . . . . . . . 608 349 57.4 404 66.5 437 71.9 466 76.6

65 and over. . . . . . . . . . . . . . . . . . 311 232 74.6 257 82.6 271 87.1 280 90.0

2012 total . . . . . . . . . . . . . . . . . . . . . 2,605 1,443 55.4 1,658 63.7 1,787 68.6 1,879 72.1

0–17 . . . . . . . . . . . . . . . . . . . . . . . 570 319 56.0 387 67.9 415 72.8 433 76.0

18–39 . . . . . . . . . . . . . . . . . . . . . . 972 419 43.1 501 51.5 558 57.4 595 61.2

40–64 . . . . . . . . . . . . . . . . . . . . . . 700 415 59.3 455 65.0 486 69.4 519 74.1

65 and over. . . . . . . . . . . . . . . . . . 363 290 79.9 315 86.8 328 90.4 332 91.5

NHANES

1999–2012 total . . . . . . . . . . . . . . . . 6,532 2,573 39.4 3,963 60.7 4,616 70.7 5,104 78.1

1999–2000 total . . . . . . . . . . . . . . . . 882 202 22.9 498 56.5 608 68.9 654 74.2

0–17 . . . . . . . . . . . . . . . . . . . . . . . 452 101 22.4 266 58.9 326 72.1 349 77.2

18–39 . . . . . . . . . . . . . . . . . . . . . . 188 34 18.1 86 45.7 117 62.2 126 67.0

40–64 . . . . . . . . . . . . . . . . . . . . . . 127 19 15.0 62 48.8 74 58.3 82 64.6

65 and over. . . . . . . . . . . . . . . . . . 115 48 41.7 84 73.0 91 79.1 97 84.4

2001–2002 total . . . . . . . . . . . . . . . . 1,199 343 28.6 702 58.6 848 70.7 935 78.0

0–17 . . . . . . . . . . . . . . . . . . . . . . . 711 219 30.8 452 63.6 534 75.1 587 82.6

18–39 . . . . . . . . . . . . . . . . . . . . . . 266 60 22.6 127 47.7 169 63.5 192 72.2

40–64 . . . . . . . . . . . . . . . . . . . . . . 108 27 25.0 54 50.0 66 61.1 72 66.7

65 and over. . . . . . . . . . . . . . . . . . 114 37 32.5 69 60.5 79 69.3 84 73.7

2003–2004 total . . . . . . . . . . . . . . . . 1,075 475 44.2 683 63.5 789 73.4 883 82.1

0–17 . . . . . . . . . . . . . . . . . . . . . . . 600 275 45.8 408 68.0 467 77.8 523 87.2

18–39 . . . . . . . . . . . . . . . . . . . . . . 258 103 39.9 143 55.4 174 67.4 196 76.0

40–64 . . . . . . . . . . . . . . . . . . . . . . 126 48 38.1 72 57.1 78 61.9 90 71.4

65 and over. . . . . . . . . . . . . . . . . . 91 49 53.9 60 65.9 70 76.9 74 81.3

2005–2006 total . . . . . . . . . . . . . . . . 911 369 40.5 558 61.3 667 73.2 730 80.1

0–17 . . . . . . . . . . . . . . . . . . . . . . . 522 217 41.6 335 64.2 407 78.0 445 85.3

18–39 . . . . . . . . . . . . . . . . . . . . . . 211 69 32.7 114 54.0 139 65.9 152 72.0

40–64 . . . . . . . . . . . . . . . . . . . . . . 111 50 45.1 64 57.7 70 63.1 78 70.3

65 and over. . . . . . . . . . . . . . . . . . 67 33 49.3 45 67.2 51 76.1 55 82.1

2007–2008 total . . . . . . . . . . . . . . . . 873 402 46.1 518 59.3 590 67.6 664 76.1

0–17 . . . . . . . . . . . . . . . . . . . . . . . 427 207 48.5 273 63.9 306 71.7 341 79.9

18–39 . . . . . . . . . . . . . . . . . . . . . . 217 85 39.2 112 51.6 132 60.8 151 69.6

40–64 . . . . . . . . . . . . . . . . . . . . . . 157 78 49.7 91 58.0 106 67.5 120 76.4

65 and over. . . . . . . . . . . . . . . . . . 72 32 44.4 42 58.3 46 63.9 52 72.2

2009–2010 total . . . . . . . . . . . . . . . . 754 346 45.9 459 60.9 512 67.9 574 76.1

0–17 . . . . . . . . . . . . . . . . . . . . . . . 299 148 49.5 201 67.2 228 76.3 257 86.0

18–39 . . . . . . . . . . . . . . . . . . . . . . 219 59 26.9 93 42.5 112 51.1 129 58.9

40–64 . . . . . . . . . . . . . . . . . . . . . . 153 79 51.6 97 63.4 103 67.3 116 75.8

65 and over. . . . . . . . . . . . . . . . . . 83 60 72.3 68 81.9 69 83.1 72 86.8

2011–2012 total. . . . . . . . . . . . . . . . . 838 436 52.0 545 65.0 602 71.8 664 79.2

0–17 . . . . . . . . . . . . . . . . . . . . . . . 339 182 53.7 234 69.0 260 76.7 290 85.6

18–39 . . . . . . . . . . . . . . . . . . . . . . 229 82 35.8 118 51.5 131 57.2 152 66.4

40–64 . . . . . . . . . . . . . . . . . . . . . . 158 85 53.8 94 59.5 108 68.4 117 74.1

65 and over. . . . . . . . . . . . . . . . . . 112 87 77.7 99 88.4 103 92.0 105 93.8

... Category not applicable.

NOTE: NCHS is National Center for Health Statistics; HUD is U.S. Department of Housing and Urban Development; NHIS is National Health Interview Survey; and NHANES is National Health and 

Nutrition Examination Survey.

SOURCES: NCHS, 1999–2012 NHIS and NHANES data linked to 1996–2014 HUD administrative records.
Series 1, No. 60  Page 17 

Table 4. Unweighted sample size and weighted percent distribution of ever-linked 2008–2012 NHIS–HUD participants aged 0–17 years, by 

selected sociodemographic and health characteristics

Characteristic

All NHIS and HUD participants Linked participants

n

Percent 

(weighted) n

Percent 

(weighted)

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62,663 51.1 1,245 49.6

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59,956 48.9 1,261 50.4

Age group (years)

0–5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40,651 34.0 712 28.8

6–11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40,969 32.9 883 38.5

12–17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40,999 33.1 911 32.7

Race and Hispanic origin

Hispanic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40,019 22.8 543 18.1

Non-Hispanic:

White. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52,740 56.1 638 31.1

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21,022 15.3 1,248 47.7

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,838 5.8 77 *3.1

Poverty level1

Below 100% of federal threshold . . . . . . . . . . . . . . . . . . . . . . . . . 31,376 21.5 1,442 59.2

100%–200% or more of federal threshold . . . . . . . . . . . . . . . . . . 30,639 23.1 700 27.5

200% or more of federal threshold . . . . . . . . . . . . . . . . . . . . . . . . 60,604 55.5 364 13.3

Health status2

Excellent/Very good . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98,889 82.7 1,801 73.0

Good. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20,975 15.3 578 22.0

Fair/Poor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,673 1.9 127 *5.0

Health insurance

No coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10,541 7.7 137 *5.3

Private insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59,576 54.8 341 14.4

Public Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38,021 26.6 1,694 67.7

Other coverage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13,691 10.3 330 12.4

* Percentage estimate may be statistically unreliable because the absolute width of its Korn-Graubard confidence interval is between 5 and 30 percentage points, yet its relative width is larger than 

130%.

1

Based on published U.S. Census Bureau poverty thresholds.

2

Self-reported.

NOTES: Missing responses are not presented. NHIS is National Health Interview Survey, and HUD is U.S. Department of Housing and Urban Development.

SOURCES: NCHS, 2008–2012 NHIS data linked to 1996–2014 HUD data.
Page 18  Series 1, No. 60

Table 5. Unweighted sample size and weighted percent distribution of ever-linked 

2008–2012 NHIS–HUD participants aged 18 and over, by selected sociodemographic 

and health characteristics 

Characteristic

All NHIS and HUD 

participants Linked participants

n

Percent 

(weighted) n

Percent 

(weighted)

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159,645 48.3 2,087 30.5

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178,897 51.7 5,977 69.5

Age group (years)

18–39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134,928 39.1 3,889 54.9

40–64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148,491 43.9 2,789 32.3

65 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55,123 17.0 1,386 12.8

Race and Hispanic origin

Hispanic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71,800 14.1 1,396 17.5

Non-Hispanic:

White. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190,468 68.4 2,949 41.1

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49,091 11.9 3,377 37.1

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27,183 5.7 342 4.3

Poverty level1

Below 100% of federal threshold . . . . . . . . . . . . . . . 50,690 12.8 4,386 48.0

100%–200% of federal threshold. . . . . . . . . . . . . . . 69,661 18.8 2,356 30.5

200% of federal threshold or more . . . . . . . . . . . . . . 218,191 68.4 1,322 21.5

Health status2

Excellent/Very good . . . . . . . . . . . . . . . . . . . . . . . . . 197,900 60.3 2,909 40.0

Good. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94,218 26.8 2,562 30.8

Fair/Poor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45,882 12.7 2,588 29.1

Health insurance

No coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67,656 17.5 1,653 23.5

Private insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . 200,361 63.2 1,681 23.0

Public insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55,963 15.3 4,255 47.7

Other coverage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11,364 3.1 452 5.3

1

Based on published U.S. Census Bureau poverty thresholds.

2

Self-reported.

NOTES: Missing responses are not presented. NHIS is National Health Interview Survey, and HUD is U.S. Department of Housing 

and Urban Development.

SOURCES: NCHS, 2008–2012 NHIS data linked to 1996–2014 HUD data.
Series 1, No. 60  Page 19

Table 6. Unweighted sample size and weighted percent distribution of ever-linked 

2009–2012 NHANES–HUD participants aged 0–17 years, by selected sociodemographic 

and health characteristics

Characteristic

All NHANES and HUD 

participants Linked participants

n

Percent 

weighted n

Percent 

weighted

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,009 50.7 336 49.1

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,893 49.3 302 50.9

Age group (years)

0–5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,318 32.9 201 25.1

6–11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,585 32.5 233 34.3

12–17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,999 34.5 204 40.6

Race and Hispanic origin

Hispanic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,354 18.9 112 16.9

Non-Hispanic:

White. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,389 56.0 97 26.6

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,894 14.2 359 45.8

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,265 10.9 70 10.6

Family income to poverty guideline ratio1

Less than 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,646 23.5 415 61.0

1 to 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,942 22.3 156 24.9

More than 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,668 47.6 50 11.1

Health status2

Excellent/Very good . . . . . . . . . . . . . . . . . . . . . . . . . 5,538 74.7 423 66.0

Good. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,925 21.0 163 26.9

Fair/Poor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 4.3 52 7.1

Health insurance 

Has coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,207 91.8 606 94.5

No coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 678 8.0 32 5.5

1

Calculated using U.S. Department of Health and Human Services poverty guidelines.

2

Self-reported. 

NOTES: Missing responses are not presented. NHANES is National Health and Nutrition Examination Survey, and HUD is U.S. 

Department of Housing and Urban Development.

SOURCES: NCHS, 2009–2012 NHANES data linked to 1996–2014 HUD data.
Page 20  Series 1, No. 60

Table 7. Unweighted sample size and weighted percent distribution of ever-linked 2009–2012 

NHANES–HUD participants aged 18 and over, by selected sociodemographic and health 

characteristics

Characteristic

All NHANES and HUD 

participants Linked participants

n

Percent 

(weighted) n

Percent 

(weighted)

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,072 48.3 339 33.3

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,319 51.7 615 66.7

Age group (years)

18–39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,653 38.7 448 52.8

40–64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,965 44.2 311 34.6

65 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,773 17.1 195 12.6

Race and Hispanic origin

Hispanic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,830 13.1 173 21.3

Non-Hispanic:

White. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,296 67.1 257 35.3

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,733 11.6 446 35.6

Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,532 8.3 78 7.8

Family income to poverty guideline ratio

Less than 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,823 15.8 506 47.1

1 to 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,984 18.9 284 32.0

More than 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,394 57.9 108 15.3

Health status1

Excellent/Very good . . . . . . . . . . . . . . . . . . . . . . . . . 4,855 47.6 267 30.1

Good. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,580 35.1 334 36.4

Fair/Poor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,952 17.2 353 33.5

Health insurance

Has coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,326 79.6 721 73.8

No coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,047 20.3 231 26.1

1

Self-reported.

NOTES: Missing responses are not presented. NHANES is National Health and Nutrition Examination Survey, and HUD is U.S. 

Department of Housing and Urban Development.

SOURCES: NCHS, 2009–2012 NHANES data linked to 1996–2014 HUD data.
Series 1, No. 60  Page 21 

Appendix I. U.S. Department of Housing and Urban Development’s 

Largest Housing Assistance Programs 

This appendix describes basic 

characteristics of the U.S. Department 

of Housing and Urban Development’s 

(HUD) largest housing assistance 

programs that are included in the linked 

National Center for Health Statistics 

(NCHS) survey and HUD files. More 

detailed information on these programs can 

be found in the Analytic Guidelines (7).

Housing Choice Vouchers 

and Related Programs 

The Housing Choice Voucher (HCV) 

program is the federal government’s 

largest housing assistance program, 

allowing low-income families, the 

elderly, and persons with disabilities 

to choose and lease safe and affordable 

housing. In the HCV program, housing 

assistance is tenant-based, meaning that 

participants find their own housing in the 

private market. Participants are free to 

choose any housing that meets program 

requirements and are not limited to units 

located in subsidized housing projects. 

For example, participants can choose 

single-family homes, townhouses, or 

apartments. When a public housing 

agency (PHA) issues a voucher to a 

family, the family is responsible for 

finding suitable housing, and the rental 

unit owner must agree to participate in 

the program. Selected units must meet 

minimal standards of health and safety 

as determined by the PHA. In the linked 

data, the HCV program also includes 

Homeownership Voucher, ProjectBased Voucher, Section 8 Moderate 

Rehabilitation, and Section 8 Rental 

Certificate programs.

 The Moving to Work (MTW) 

demonstration program was introduced to 

give PHAs flexibility with public housing 

(PH) and HCV programs. Participants in 

HCV programs may be served by either 

MTW or non-MTW PHAs, which have 

different mandates for data completeness 

and frequency of recertification. More 

information on the MTW demonstration 

project can be found in the Analytic 

Guidelines (7).

Multifamily Programs 

The multifamily (MF) program 

category in the linked NCHS–HUD 

data encompasses a number of separate, 

distinct HUD programs, including: 

Section 221(d)(3) Below Market 

Interest Rate, Section 236 Multifamily 

Housing, Rental Assistance, ProjectBased Section 8 (or PBS8) Voucher 

Assistance in Multifamily Housing, 

Section 202 Supportive Housing for the 

Elderly Program, Section 202/162—

Project Assistance Contract, Section 

811 Supportive Housing for Persons 

with Disabilities, and Rent Supplement. 

Because each of these programs lacked 

sufficient sample size on an individual 

basis in the linked file, they were 

combined into a single MF program 

category in the linked data files.

In all MF programs, subsidies are 

paid directly to private property owners 

who provide a certain percentage of 

their housing units at affordable rates 

for low-income persons who qualify. 

Ownership may be for-profit or nonprofit. 

HUD subsidies (i.e., rental subsidies, 

below-market interest financing, insured 

mortgages, and other forms of assistance) 

typically are linked with ongoing rental 

assistance for annual operating costs. 

MF program assistance is tied to the 

property, unlike tenant-based rental 

assistance programs (e.g., HCVs), and 

tenants cannot take their rental housing 

assistance subsidy elsewhere. Assistance 

always stays with the owner of the 

development during the duration of their 

assistance contract. 

Public Housing 

The PH program was established to 

provide safe rental housing for eligible 

low-income families, the elderly, and 

persons with disabilities. PH dwellings 

range from scattered-site single-family 

detached houses to high-rise apartment 

buildings. HUD provides capital 

subsidies and operating subsidies to 

local PHAs that manage public housing 

for eligible low-income residents. HUD 

also provides technical assistance to help 

PHAs plan, develop, and manage PH 

developments. 

For PH residents, income must be 

verified at re-examination periods every 

12–18 months. At re-examination, if 

the person’s or family’s income exceeds 

80% of area median income, then PHA 

may reassess their eligibility for public 

housing. In PH programs, specific 

calculations are used to determine a 

tenant’s monthly rent amount. 

As with tenants in an HCV program, 

tenants participating in PH programs may 

be served by either MTW or non-MTW 

PHAs, which have different mandates 

for data completeness and frequency 

of recertification. More information on 

the MTW demonstration project can be 

found in the Analytic Guidelines (7).
Page 22  Series 1, No. 60

Appendix II. Summary of Linked National Center for Health Statistics–

U.S. Department of Housing and Urban Development Data 

Table I. Linked NCHS–HUD data files: Name, population, and description

Data files Universe Description

Feasibility: 

1999–2012 NHIS–HUD

1999–2012 NHANES–HUD

All 1999–2012 NHIS and NHANES participants NCHS created two feasibility files for each linked survey 

file to aid researchers performing sample size and 

power calculations for potential analyses. The feasibility 

files contain linkage eligibility information and program 

participation indicators for each 1999–2012 NHIS and 

NHANES participant. See Analytic Guidelines for details on 

using these files to determine sample size.

Transaction All 1999–2012 NHIS and NHANES participants

linked to HUD administrative data

This file contains each transaction of the linked 1999–2012 

NHIS–HUD and NHANES–HUD participants. As noted in 

Analytic Guidelines, transactions for children were removed 

if the transaction occurred after the child’s 18th birthday. 

Episode:

Episode_dates All 1999–2012 NHIS and NHANES participants 

linked to HUD administrative data

Seven episode files contain start and end dates for 

participation in HUD programs, based on transaction data 

and assumptions about reasonable intervals between 

transactions. Because most HUD recipients must recertify 

each year, a transaction is expected each year. However, 

certain HUD program categories (e.g., Moving to Work) 

have longer intervals between recertifications. See Analytic 

Guidelines for details on construction of the episode files.

Episode dates–MTW HCV Linked participants with at least one Moving to

Work Housing Choice Voucher transaction

Episode dates–MTW PH Linked participants with at least one Moving to

Work public housing transaction

Episode dates–Other MF Linked participants with at least one Other

multifamily transaction

Episode dates–PBS8 Linked participants with at least one multifamily 

project-based Section 8 transaction

Episode dates–PH Linked participants with at least one public 

housing transaction

Episode dates–HCV Linked participants with at least one Housing 

Choice Voucher transaction

Concurrency All 1999–2012 NHIS and NHANES participants

linked to HUD administrative data

This file contains variables related to the timing of HUD 

housing participation relative to NCHS survey participation, 

such as indicator variables for receipt of HUD housing 

assistance at the time of survey; type of HUD housing 

assistance received; and amount of time between last 

and next transaction. See Analytic Guidelines for details 

on using concurrency variables to identify participants 

receiving HUD housing assistance at interview.

Weights All 1999–2012 NHIS and NHANES participants Although NHIS and NHANES are designed to be nationally 

representative of the U.S. civilian noninstitionalized 

population, not all NCHS survey participants are eligible for 

linkage. Specific weights have been calculated for analyses 

of these surveys when using linked data. One weights file 

contains a single record for all participants of 1999–2012 

NHIS and NHANES, as well as various survey weights 

adjusted for linkage eligibility.

NOTES: NHIS is National Health Interview Survey, and NHANES is National Health and Nutrition Examination Survey. HUD is U.S. Department of Housing and Urban Development, and NCHS is 

National Center for Health Statistics. Analytic Guidelines is available from: https://www.cdc.gov/nchs/data/datalinkage/nchs_hud_analytic_considerations.pdf. 

SOURCES: NCHS, 1999–2012 NHIS and NHANES data linked to 1996–2014 HUD data.
Series 1, No. 60  Page 23 

Appendix III. Data Variable Considerations 

The following variables may be 

useful for researchers using the linked 

National Center for Health Statistics 

(NCHS) and U.S. Department of Housing 

and Urban Development (HUD) data 

because they provide information about 

whether the survey participant was linked 

to the HUD administrative data and 

the timing of receipt of HUD housing 

assistance relative to the survey interview 

and examination date:

● HUD_MATCH_STATUS—This 

variable can be used to identify 

participants who were eligible for 

linkage and who were linked to the 

HUD administrative data.

● Concurrency variables—These 

binary indicator variables indicate 

whether the survey participant 

received HUD housing assistance at 

the time of interview or examination. 

The 20 variables are characterized 

by HUD program category (Housing 

Choice Voucher [HCV], multifamily 

[MF], and public housing [PH]) and 

subprogram (non-Moving to Work 

[MTW] HCV, MTW HCV, nonMTW PH, MTW PH, Project-Based 

Section [PBS] 8, and non-PBS8 

MF) at time of concurrency, and 

by concurrency at time of survey 

interview or examination (NHANES 

only):

Concurrency by Program 

(HCV, MF, PH)

Concurrency at survey interview

● CON_STATUS_INT: Lived in any 

type of HUD-assisted housing at 

time of interview 

● CON_STATIN_HCV: Lived in HCV 

HUD-assisted housing at time of 

interview 

● CON_STATIN_MF: Lived in MF 

HUD-assisted housing at time of 

interview 

● CON_STATIN_PH: Lived in PH 

HUD-assisted housing at time of 

interview

Concurrency at examination 

(NHANES only)

● CON_STATUS_EXM: Lived in any 

type of HUD-assisted housing at 

time of examination 

● CON_STATEX_HCV: Lived in 

HCV HUD-assisted housing at time 

of examination

● CON_STATEX_MF: Lived in MF 

HUD-assisted housing at time of 

examination

● CON_STATEX_PH: Lived in PH 

HUD-assisted housing at time of 

examination 

Concurrency by 

Subprogram (non-MTW 

HCV, MTW HCV,

non-MTW PH, MTW PH, 

PBS8 MF, non-PBS8 MF)

Concurrency at survey interview

● INT_HCV: Lived in non-MTW HCV 

HUD-assisted housing at time of 

interview 

● INT_MTW_HCV: Lived in MTW–

HCV HUD-assisted housing at time 

of interview 

● INT_PH: Lived in non-MTW PH 

HUD-assisted housing at time of 

interview 

● INT_MTW_PH: Lived in MTW–PH 

HUD-assisted housing at time of 

interview 

● INT_PBS8: Lived in PBS8 MF 

HUD-assisted housing at time of 

interview 

● INT_OTHER_MF: Lived in nonPBS8 MF HUD-assisted housing at 

time of interview 

Concurrency at examination 

(NHANES only)

● EXM_HCV: Lived in non-MTW 

HCV HUD-assisted housing at time 

of examination 

● EXM_MTW_HCV: Lived in MTW–

HCV HUD-assisted housing at time 

of examination 

● EXM_PH: Lived in non-MTW PH 

HUD-assisted housing at time of 

examination 

● EXM_MTW_PH: Lived in MTW 

PH HUD-assisted housing at time of 

examination 

● EXM_PBS8: Lived in PBS8 MF 

HUD-assisted housing at time of 

examination 

● EXM_OTHER_MF: Lived in nonPBS8 MF HUD-assisted housing at 

time of examination 

The following 16 variables are 

related to the timing of HUD assistance 

relative to the survey interview or 

examination for each HUD program 

category (HCV, MF, and PH). Although 

these variables cannot be directly 

accessed by researchers, researchers can 

develop their own categorical variables 

based on the following:

HUD Transactions 

Occurring After Survey

Number of days between 

interview and next HUD 

transaction

● TIME_A_INT: Number of days 

between interview and subsequent 

HUD transaction

● TIME_A_HCV_INT: Number 

of days between interview and 

subsequent HCV transaction

● TIME_A_MF_INT: Number of days 

between interview and subsequent 

MF transaction

● TIME_A_PH_INT: Number of days 

between interview and subsequent 

PH transaction

Number of days between 

examination and next HUD 

transaction (NHANES only)

● TIME_A_EXM: Number of days 

between examination and subsequent 

HUD transaction

● TIME_A_HCV_EXM: Number 

of days between examination and 

subsequent HCV transaction
Page 24  Series 1, No. 60

● TIME_A_MF_EXM: Number of 

days between examination and 

subsequent MF transaction

● TIME_A_PH_EXM: Number of 

days between examination and 

subsequent PH transaction

HUD Transactions 

Occurring Before Survey

Number of days between 

interview and previous HUD 

transaction

● TIME_B_INT: Number of days 

between interview and previous 

HUD transaction

● TIME_B_HCV_INT: Number of 

days between interview and previous 

HCV transaction

● TIME_B_MF_INT: Number of days 

between interview and previous MF 

transaction

● TIME_B_PH_INT: Number of days 

between interview and previous PH 

transaction

Number of days between 

examination and previous HUD 

transaction (NHANES only)

● TIME_B_EXM: Number of days 

between examination and previous 

HUD transaction

● TIME_B_HCV_EXM: Number 

of days between examination and 

previous HCV transaction

● TIME_B_MF_EXM: Number of 

days between examination and 

previous MF transaction

● TIME_B_PH_EXM: Number of 

days between examination and 

previous PH transaction
Series 1, No. 60  Page 25 

Appendix IV. Evaluation of NCHS–HUD Data Linkage: Comparison 

With HUD Program Recipients

This analysis assesses whether 

similarities or differences occur between 

the linked National Center for Health 

Statistics (NCHS) survey participants 

and all recipients of U.S. Department 

of Housing and Urban Development 

(HUD)-assisted housing. The percent 

distribution of selected characteristics 

from all HUD housing assistance 

recipients are presented side by side 

with that from a sample of linked 

NCHS–HUD participants who received 

assistance during the same time period. 

This evaluation uses only 1 year of 

data (2012) from the National Health 

Interview Survey (NHIS) and two cycles 

(2009–2012) of the National Health 

and Nutrition Examination Survey 

(NHANES). 

The NCHS–HUD linked samples 

from the 2012 NHIS and the 2009–2012 

NHANES are included in this analysis; 

however, only variables derived from 

the HUD administrative data and not the 

NCHS survey data are described in the 

presentations, mainly because the HUD 

administrative data are the only data 

source available for both the NCHS–

HUD linked sample and the population 

of HUD housing assistance recipients not 

included in the linked sample. Although 

some of these variables (e.g., sex, age, 

and total number of household members) 

are also collected in the NCHS survey, 

the mechanism for data collection differs 

between administrative and survey data. 

Analyses of these variables from the 

survey data may yield different results. 

This analysis is not intended to evaluate 

the HUD administrative data, but rather 

to present characteristics of both the 

NCHS–HUD linked sample and the 

population of HUD housing assistance 

recipients. The following variables are 

included in the analysis: 

● HUD program category—Housing 

Choice Voucher (HCV), multifamily 

(MF), and public housing (PH)

● Sex (male and female)

● Age (0–17, 18–29, 30–44, 45–61, and 

62 and over; age groups are based on 

categories used in HUD reports or 

publications)

● Indicator for households with at least 

one disabled person, based on HUD’s 

operational definition of disability: 

https://portal.hud.gov/hudportal/

HUD?src=/program_offices/

fair_housing_equal_opp/disabilities/

inhousing

● Indicator for households with at least 

one elderly person (HUD defines 

elderly as age 62 and over; therefore, 

for this comparison, age 62 was 

used as the threshold to define a 

household with an elderly person)

● Number of bedrooms in unit (0–1, 2, 

3, and 4 or more) 

● Total household members (1, 2, 3, 4, 

and 5 or more) 

The following criteria are used to 

assess similarities and differences in the 

selected sociodemographic and household 

characteristics between the linked survey 

participants and all recipients of HUDassisted housing:

1. If the percentage for each category 

(e.g., male and female) of a 

characteristic (e.g., sex) is equal in 

both populations, it is described as 

being the same. 

2. If the relative difference between the 

two populations, defined as

| XHUDpopulation – Xlinked | / XHUDpopulation

is between 0.0 and 0.1 for all 

categories of the characteristic, 

concurrent linked survey 

participants are described as 

“consistent or similar” to all 

recipients of HUD-assisted housing 

with respect to that characteristic. 

3. If the relative difference between 

the two populations for at least 

one category of the characteristic 

is 0.1 or greater, concurrent linked 

survey participants are described 

as “different (higher/more or lower/

less)” than all recipients of HUDassisted housing with respect to that 

characteristic. 

Because the two populations are not 

statistically independent and measures of 

correlation between the two populations 

were not readily available, comparisons 

were not statistically tested.

Evaluation of Linked 2012 

NHIS–HUD Data: Methods

Recipients of HUD housing 

assistance during the 2012 calendar 

year were identified based on HUD 

administrative records with effective 

dates of Nov. 1, 2011, through Feb. 

28, 2013. Only the most recent HUD 

transaction was retained so that each 

individual was counted only once. 

In this analysis, these HUD housing 

assistance recipients are referred to as the 

population of “all 2012 HUD-assisted 

tenants.” Concurrent 2012 NHIS–HUD 

participants are, in theory, a subset of this 

population. Similarities and differences 

between the concurrent 2012 NHIS–

HUD participants and all 2012 HUDassisted tenants demonstrate ways in 

which the linked data may or may not be 

comparable to the population of HUD 

housing assistance recipients. 

The NHIS sample adult and sample 

child weights were used in the analyses 

to account for unequal probabilities 

of selection and survey nonresponse, 

and were further adjusted for linkage 

eligibility via poststratification by 

age, race and ethnicity, and sex, using 

SUDAAN’s procedure WTADJUST 

(16). Reweighting of the linked survey 

data ensures that population totals 

are maintained and helps account for 

potential linkage consent bias. The 

confidence intervals incorporate the 

complex sample design of NHIS. 

Evaluation of Linked 2012 

NHIS–HUD Data: Results

A total of 1,434 NHIS 2012 

participants were concurrently linked 

to HUD administrative data. During the 

2012 time frame, the HUD administrative 
Page 26  Series 1, No. 60

records contained data on 9,790,425 

HUD recipients. Results are presented in 

Appendix Table II and Appendix Figures 

I–IV. 

For both populations, the HCV 

program had the highest participation 

(53.7% among all 2012 HUD-assisted 

tenants and 49.7% among concurrent 

2012 NHIS–HUD participants). The 

percentage of persons in MF units among 

all 2012 HUD-assisted tenants was lower 

(23.1%) than among concurrent 2012 

NHIS–HUD participants (29.5%), and 

the percentage of all 2012 HUD-assisted 

tenants in PH units was higher (23.3%) 

than among concurrent 2012 NHIS–HUD 

participants (20.8%). 

Concurrent 2012 NHIS–HUD 

participants were 63.8% female and 

36.2% male, which was similar to the 

distribution by sex among all 2012 HUDassisted tenants. The age distributions 

were similar between the two populations 

for most age groups. However, the 

percentage of adults aged 30–44 was 

lower among all 2012 HUD-assisted 

tenants (13.7%) than among concurrent 

2012 NHIS–HUD participants (15.9%). 

A higher percentage of all 2012 

HUD-assisted tenants lived in households 

with a disabled person (26.2%) compared 

to concurrent 2012 NHIS–HUD 

participants (21.0%). Consistent with 

the population of all 2012 HUD-assisted 

tenants (18.6%), 18.3% of concurrent 

2012 NHIS–HUD participants lived in 

a household with an elderly person. The 

distribution of unit size was consistent 

between the two populations. The 

distribution of total household members 

was similar between the two populations 

in all categories except for the 5 or more 

category; the population

of all 2012 HUD-assisted tenants had 

more individuals living in households 

with 5 or more members (20.8%) than 

the population of concurrent 2012 

NHIS–HUD participants (17.4%).

Evaluation of Linked 

2009–2012 NHANES–HUD 

Data: Methods

Two NHANES cycles were 

pooled due to the small sample size of 

concurrently linked NHANES–HUD

Table II. Number and percent distribution of concurrently linked 2012 NHIS–HUD participants and 2012 HUD-assisted tenants, by HUD 

program and selected HUD-collected demographic characteristics

HUD program and demographic characteristics

2012 HUD-assisted 

tenants

2012 concurrently linked NHIS–HUD participants 

(n = 1,434)

n Percent n

Percent 

(weighted)

95% CI

Low High

HUD housing category

Housing Choice Voucher . . . . . . . . . . . . . . . . . . . . . . . 5,252,249 53.7 635 49.7 44.4 55.1

Multifamily housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,256,365 23.1 441 29.5 23.8 35.9

Public housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,281,811 23.3 358 20.8 16.3 26.1

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,665,200 37.4 460 36.2 32.5 40.0

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,124,452 62.6 973 63.8 60.0 67.5

Age group (years)

0–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,931,683 40.2 318 37.2 33.9 40.6

18–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,443,686 14.8 217 16.0 13.5 18.7

30–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,341,524 13.7 270 15.9 13.8 18.4

45–61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,474,394 15.1 269 15.0 12.3 18.1

62 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,599,095 16.3 360 15.9 13.2 19.0

Households

With disabled persons . . . . . . . . . . . . . . . . . . . . . . . . . 2,567,030 26.2 333 21.0 17.7 27.7

With elderly persons . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,824,617 18.6 383 18.3 15.3 21.8

Unit size (number of bedrooms)

0–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,104,962 21.5 486 20.3 17.2 23.8

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,936,021 30.0 488 32.8 28.7 37.2

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,543,478 36.2 359 34.7 30.4 39.3

4 or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,205,964 12.3 101 *12.2 9.1 16.3

Total household members

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,221,424 22.7 551 23.1 19.8 26.7

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,834,022 18.7 307 20.0 17.3 23.0

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,978,692 20.2 264 21.5 18.0 25.5

4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,721,379 17.6 165 17.9 14.6 21.9

5 or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,034,144 20.8 136 17.4 13.7 21.8

* Figure may be statistically unreliable because the absolute width of its Korn-Graubard confidence interval (CI) is between 5 and 30 percentage points, yet its relative width is larger than 130%. 

NOTES: CIs for percentages are calculated using SUDAAN with the Korn-Graubard adjustment to the Clopper-Pearson method. NHIS is National Health Interview Survey, and HUD is U.S. Department 

of Housing and Urban Development.

SOURCES: NCHS, linked NHIS–HUD data sample, 2012; HUD administrative data, 2012.
Series 1, No. 60  Page 27 

participants for a single cycle. Recipients 

of HUD housing assistance with effective 

dates from Nov. 1, 2008, through 

Feb. 28, 2013, were identified from the 

HUD administrative records and included 

in the analysis to conservatively capture 

all HUD housing assistance recipients 

from the 2009–2012 calendar years. 

If more than one record existed per 

individual, only the most recent record 

was retained, so that each person was 

counted once at most. In this analysis, 

these HUD housing assistance recipients 

are referred to as the population of “all 

2009–2012 HUD-assisted tenants.” 

Concurrent 2009–2012 NHANES–HUD 

participants are, in theory, a subset of this 

population. Similarities and differences 

between the concurrent 2009–2012 

NHANES–HUD participants and all 

2009–2012 HUD-assisted tenants 

demonstrate ways in which the linked 

data may or may not be comparable to the 

population of HUD housing assistance 

recipients. 

The sample weights, accounting 

for unequal probabilities of selection 

and survey nonresponse, were further 

adjusted for linkage eligibility via 

poststratification by age, race and ethnicity, 

and sex using SUDAAN’s WTADJUST 

(16). Reweighting of the linked survey data 

ensures that population totals are maintained 

and helps account for potential linkage 

consent bias. The confidence intervals 

reflect the complex design of NHANES. 

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHIS is National Health 

Interview Survey. All variables shown are based on HUD administrative data.

SOURCES: NCHS, linked NHIS–HUD data sample, 2012; HUD administrative data, 2012. 

All 2012

HUD-assisted

tenants

2012 NHIS–HUD linked

and concurrent

participants

95% CI

 

Figure I. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD 

participants, by HUD housing category

Figure II. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants, by sex and age group

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHIS is National Health Interview Survey. All variables shown are based on HUD 

administrative data.

SOURCES: NCHS, linked NHIS–HUD data sample, 2012; HUD administrative data, 2012. 

 
Page 28  Series 1, No. 60

Evaluation of Linked

2009–2012 NHANES–HUD 

Data: Results

A total of 782 NHANES 2009–2012 

participants were concurrently linked 

to HUD administrative data. During 

the 2009–2012 time frame, the HUD 

administrative records contained data 

on 14,148,465 HUD recipients. Results 

are presented in Appendix Table III and 

Appendix Figures V–VIII. 

In both populations, the HCV 

program was the most common housing 

assistance program. Compared to all 

2009–2012 HUD-assisted tenants, 

concurrent 2009–2012 NHANES–HUD 

participants received more assistance 

through HCV programs (60.4% 

compared to 54.3%, respectively) and 

fewer received assistance through MF 

(17.6% compared to 20.9%) and PH 

programs (22.0% compared to 24.7%). 

The percentages of concurrent 

2009–2012 NHANES–HUD participants 

that were female (65.2%) and male 

(34.8%) were consistent with those of 

all 2009–2012 HUD-assisted tenants 

(females 61.6%, males 38.4%). For three 

of the five age categories, no differences 

were observed between the two populations. 

However, more concurrent 2009–2012 

NHANES–HUD participants were aged 

45–61 compared with all 2009–2012 

HUD-assisted tenants (18.4% compared to 

13.7%), and fewer were aged 18–29 (13.6% 

compared to 17.2%).

Figure III. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD 

participants, by percentage of households with disabled or elderly persons

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHIS is National Health 

Interview Survey. All variables shown are based on HUD administrative data.

SOURCES: NCHS, linked NHIS–HUD data sample, 2012; HUD administrative data, 2012. 

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHIS is National Health Interview Survey. All variables shown are based on HUD 

administrative data.

SOURCES: NCHS, linked NHIS–HUD data sample, 2012; HUD administrative data, 2012. 

 

Figure IV. All 2012 HUD-assisted tenants and concurrently linked 2012 NHIS–HUD participants, by household characteristics
Series 1, No. 60  Page 29 

Table III. Number and percent distribution of concurrently linked 2009–2012 NHANES–HUD participants and 2009–2012 HUD-assisted 

tenants, by HUD program and selected HUD-collected demographic characteristics

HUD program and 

demographic characteristics

2009–2012 HUD-assisted 

tenants

2009–2012 concurrently linked 

NHANES–HUD participants 

(n = 782)

n Percent n

Percent 

(weighted)

95% CI

Low High

HUD housing category

Housing Choice Voucher . . . . . . . . . . . . . . . . . . . . . . . 7,685,573 54.3 436 60.4 48.5 71.2

Multifamily housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,962,641 20.9 167 *17.6 11.9 25.2

Public housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,500,251 24.7 179 22.0 12.9 34.9

Sex

Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,436,525 38.4 317 34.8 30.7 39.2

Female. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,710,946 61.6 465 65.2 60.9 69.4

Age group (years)

0–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,683,455 40.2 332 37.3 31.5 43.4

18–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,431,653 17.2 79 13.6 10.5 17.4

30–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,897,090 13.4 79 13.8 11.7 16.2

45–61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,935,830 13.7 111 18.4 15.3 21.9

62 and over. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,200,128 15.6 181 17.0 12.8 22.2

Households

With disabled persons . . . . . . . . . . . . . . . . . . . . . . . . . 3,588,153 25.4 151 23.2 17.1 30.6

With elderly persons . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,508,121 17.7 195 18.9 14.4 24.5

Unit size (number of bedrooms)

0–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,974,052 21.0 182 20.4 14.8 27.6

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,142,288 29.3 189 23.8 18.6 29.9

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,246,890 37.1 320 45.3 40.2 50.5

4 or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,785,235 12.6 91 *10.5 6.9 15.6

Total household members

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,166,498 22.4 201 23.8 18.2 29.3

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,443,175 17.3 122 14.6 11.8 18.0

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,897,762 20.5 158 21.7 17.2 27.1

4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,577,165 18.2 132 19.3 14.9 24.5

5 or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,045,711 21.6 162 21.1 14.8 29.2

* Figure may be statistically unreliable because it is based on fewer than 8 degrees of freedom. 

NOTES: Confidence intervals (CIs) for percentages are calculated using SUDAAN with the Korn-Graubard adjustment to the Clopper-Pearson method. NHANES is National Health and Nutrition 

Examination Survey, and HUD is U.S. Department of Housing and Urban Development.

SOURCES: NCHS, linked NHANES–HUD data sample, 2009–2012; HUD administrative data, 2009–2012.
Page 30  Series 1, No. 60

Similar percentages of all 2009–2012 

HUD-assisted tenants (25.4%) and 

concurrent 2009–2012 NHANES–HUD 

participants (23.2%) lived in a household 

containing a disabled person. Consistent 

with the population of all 2009–2012 

HUD-assisted tenants (17.7%), 18.9% of 

concurrent 2009–2012 NHANES–HUD 

participants lived in a household containing 

an elderly person. The distribution of unit 

size differed between the two populations 

for all categories except the 0–1 number 

of bedrooms category. The distribution 

of total household members was similar 

between the two populations except for the 

category with a household size of two: The 

population of all 2009–2012 HUD-assisted 

tenants had more individuals living in 

households with a size of two (17.3%) than

the population of concurrent 2009–2012 

NHANES–HUD participants (14.6%).

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHANES is National 

Health and Nutrition Examination Survey. All variables shown are based on HUD administrative data.

SOURCES: NCHS, linked NHANES–HUD data sample, 2009–2012; HUD administrative data, 2009–2012. 

 

Figure V. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 

NHANES–HUD participants, by HUD housing category

Figure VI. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD participants, by sex and age group

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHANES is National Health and Nutrition Examination Survey.

All variables shown are based on HUD administrative data.

SOURCES: NCHS, linked NHANES–HUD data sample, 2009–2012; HUD administrative data, 2009–2012. 
Series 1, No. 60  Page 31 

Conclusion 

The linked NCHS–HUD data 

represent a sample of the civilian 

noninstitutionalized U.S. population 

living in HUD-assisted housing at some 

point in the administrative period and 

may or may not be comparable to the 

overall population of HUD assistance 

recipients. Among concurrent linked 

NHIS–HUD and NHANES–HUD 

participants, the percentages of males 

and females and the percentage of those 

living in a household with an elderly 

person were similar to the corresponding 

percentages among all HUD tenants. 

Differences between the two populations 

were observed by program category 

of HUD housing assistance received, 

age, household disability status, size 

of unit, and total number of household 

members. Differences in characteristics 

that were not measured here (e.g., 

income and health insurance coverage, 

among others) between concurrent linked 

survey participants and the population 

of HUD housing assistance recipients 

should also be taken into consideration. 

These differences may impact the 

generalizability of study results from 

analyses of the linked NCHS–HUD data 

to the overall population of HUD housing 

assistance recipients.

Figure VII. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 

NHANES–HUD participants, by percentage of households with disabled or elderly persons

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHANES is National 

Health and Nutrition Examination Survey. All variables shown are based on HUD administrative data.

SOURCES: NCHS, linked NHANES–HUD data sample, 2012; HUD administrative data, 2012. 

 

NOTES: CI is confidence interval. HUD is U.S. Department of Housing and Urban Development; NHANES is National Health and Nutrition Examination Survey. All variables shown are 

based on HUD administrative data.

SOURCES: NCHS, linked NHANES–HUD data sample, 2009–2012; HUD administrative data, 2009–2012. 

Figure VIII. All 2009–2012 HUD-assisted tenants and concurrently linked 2009–2012 NHANES–HUD participants, by household 

characteristics
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