National Center for Health Statistics

Does the Decade Matter? Examining the Impact of 

Using Geocodes from Different Decades in the 

Analysis of Merged Survey and Contextual Data

Jessie L. Parker, Health Statistician, Data Linkage Program

Data Linkage Methodology and Analysis Branch

Division of Analysis and Epidemiology

FCSM Research & Policy Conference

October 26, 2023
Background and outline

 The National Center for Health Statistics (NCHS) Data Linkage Program enhances 

the analytic utility of NCHS survey data by linking with administrative records

 Additionally, NCHS geocodes survey participant addresses which allows 

researchers to merge the survey data with geographic information from other 

sources

 This presentation will cover: 

– The NCHS Data Linkage Program

– Introduction to geocodes

– Examples of research using NCHS geocodes

– A brief demonstration comparing 2010 and 2020 geocodes

– How to access NCHS linked data
NCHS surveys used in linkages and geocoding

National Health Interview Survey (NHIS)

A nationally representative, cross-sectional sample of the US civilian 

noninstitutionalized population, which includes a household interview survey that 

serves as an important source of information on the nation’s health

National Health and Nutrition Examination Survey (NHANES)

A nationally representative, cross-sectional sample of the US civilian 

noninstitutionalized population, which includes a household interview followed by 

an examination in a mobile examination center that serves as an important source 

of information on the health and nutritional status of adults and children

National Hospital Care Survey (NHCS) 

NHCS collects data on patient care in hospital-based settings (inpatient, 

emergency, and outpatient departments) to describe patterns of health care 

delivery and utilization in the US 
NCHS Survey Data

Population-based 

household surveys

National healthcare surveys

Receipt/type of housing 

assistance

Housing and Urban 

Development

Cause of death from 

National Death Index

Mortality

Medicare and Medicaid 

Healthcare utilization and 

expenditures

Geocoded 

Addresses 

Add contextual 

information to standard 

Census geocoded areas

Service records and 

benefit utilization

Department of 

Veterans Affairs

Examine factors 

associated with ESRD

NCHS linked End Stage Renal Disease

data 
What is geocoding?

 Geocoding is the process of assigning an address to:

– A specific location on a map

– Exact coordinates (latitude, longitude)

– Other statistical/administrative areas (e.g., census tracts)

 Requires a frame of reference (e.g., street map) and 

locational information (e.g., residential address) for 

each entity 

 NCHS partners with the Department of Housing and 

Urban Development to leverage their enterprise 

geocoding services
Why do we geocode?

 Allow researchers to combine neighborhood and ecological 

information with individual survey data

 Expand use of geocoded data to improve public health 

 Types of geocoded data sources

– Air quality and climate data 

– Built environment indicators (e.g., traffic, walkability scores)

– Neighborhood-level socioeconomic and demographic characteristics

– Food deserts

– Access to healthcare
Examples of research using geocoded data

Zip codes

D Huang et al. Twitter-Derived Social Neighborhood Characteristics and Individual-Level 

Cardiometabolic Outcomes: Cross-Sectional Study in a Nationally Representative Sample. 

JMIR Public Health Surveill. 2020 Jul-Sep; 6(3): e17969. 

Census tracts

MA Fleisch et al. Relationships between social isolation, neighborhood poverty, and cancer 

mortality in a population-based study of US adults. PLoS One, 2017 12(3): p. e0173370. 

Census blocks

J Barry. The Relationship Between the Supply of Primary Care Physicians and Measures of 

Breast Health Service Use. J Womens Health (Larchmt). 2017 May;26(5):511-519. 

Residential addresses

Parker JD, Kravets N, Nachman K, Sapkota A. Linkage of the 1999–2008 National Health and 

Nutrition Examination Surveys to traffic indicators from the National Highway Planning 

Network. National Health Statistics Reports; no 45. Hyattsville, MD: National Center for 

Health Statistics. 2012. 
Geocoded NCHS restricted use survey data

 Available: 2000, 2010, 2020 Census Codes

 Surveys are geocoded to census blocks/tracts across 

multiple decennials to support longitudinal analysis 

Variables Description

Block Census block 

Block Group Census block group

Tract Census tract

County FIPS county code

LAT Latitude

LON Longitude

MSA Metropolitan Statistical Area Code
What survey years have geocode data available?

NCHS Survey Census 2000 Census 2010 Census 2020

NHIS 1986-2016

*** *** ***

NHIS 2017-2021

*** ***

NHANES 1999-2016

*** *** ***

NHANES 2017-2020

*** ***

NHCS 2016

*** ***
Examples of contextual information available at geocode level

 Social Determinants of Health (SDOH) Database

– Created by the Agency for Healthcare Research and Quality (AHRQ)

– Contains information across five key SDOH domains: social context, economic 

context, education, physical infrastructure, and healthcare context

– Available at county, ZIP code, and census tract levels

 Census Demographic Profile

– Created by US Census Bureau

– Contains demographic and housing information

– Available at census tract level as lowest level of geography

 EJScreen: Environmental Justice Screening and Mapping Tool

– Created by Environmental Protection Agency (EPA)

– Contains information on pollution, health disparities, climate change, and more

– Available at census block group and tract level
Exploratory demonstration

 Linked geocoded 2016 

NHIS participants to census 

tract level information in 

the AHRQ SDOH database

 Address information is 

from the time of the survey 

(2016 for all participants)

 Limited to sample adults 

(n=33,028)

 Analysis is unweighted

27.2% 31.7%

82.3%

0%

20%

40%

60%

80%

100%

Census tract Block group Census block

PERCENT OF NHIS 2016 

SAMPLE ADULTS WITH 

CHANGE IN GEOCODE ID, 

2010 VS 2020
Variables selected from AHRQ SDOH Database

Domain Topic Data 

Source Variable Name Variable Label

Economic 

context Poverty

ACS ACS_PCT_PERSON_I

NC_BELOW99

Percentage of population with an 

income to poverty ratio under 

1.00

Education Attainment ACS ACS_PCT_LT_HS

Percentage of population with 

less than high school education 

(ages 25 and over)

ACS = American Community Survey (US Census Bureau)
Change over time by census tract for 2016 NHIS sample adults*

2010 Census Tracts 

mean (median)

2020 Census Tracts 

mean (median)

Percentage of population with income to 

poverty ratio under 1.00

14.0% (10.9%) 13.5% (10.3%)

Percentage of population with less than 

high school education 

14.0% (11.4%) 10.7% (8.2%)

* Analyses are unweighted

• Change is due to both administrative changes (boundary redefinitions 

and renumbering) and real change over time (2010 vs 2020)
Percentage of population in 2016 NHIS sample adult’s census tract 

with income to poverty ratio under 1.00, 2010 vs 2020*

* Analyses are unweighted

0%

5%

10%

15%

20%

25%

Percent

2010 Census Tracts 2020 Census Tracts
Percentage of population in 2016 NHIS sample adult’s census 

tract with less than a high school education, 2010 vs 2020*

* Analyses are unweighted

0%

5%

10%

15%

20%

25%

Percent

2010 Census Tracts 2020 Census Tracts
Key summary points

 In addition to maintaining and updating linkages between NCHS 

survey data and administrative data, the NCHS Data Linkage 

Program also geocodes survey participant addresses

 Contextual information on the geographic area, including 

socioeconomic and environmental characteristics, can be merged 

into the linked data and examined along with survey and 

administrative data

 While address is always from the time of the interview, the time 

period of the geocodes should be carefully considered as the 

choice may impact results, due to real change over time and/or 

administrative changes
How to access restricted-use NCHS linked data

• Research Data Portal allows users to search all available data and 

use proposal building tool for data requests following the Standard 

Application Process (SAP): https://www.researchdatagov.org/ 
NCHS Data Linkage Program

Subscribe to the NCHS Data Linkage Program LISTSERV to receive updates! Email a message to 

list@cdc.gov. Leave the subject line blank. In the body of the message, type: 

– SUBSCRIBE NCHS-DATA-LINKAGE-PROGRAM lastname, firstname

Contact me at: Jessie.Parker@cdc.hhs.gov

Contact the Data Linkage Program: datalinkage@cdc.gov

Visit our website: www.cdc.gov/nchs/data-linkage

Thank you!
For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.