Table 2.

Methods and File Organization of Nationally Representative Surveys of the US Population

Survey	Design	Oversampling	Method	File organization*
BRFSS, BRFSS-SMART	Cross-sectional sample of non-institutionalized US population	48 states sampled disproportionately from sub-state regions (to increase sample size for smaller geographically-defined populations of interest)	Telephone (including cellular since 2011), Internet. Data collected monthly in each state and territory.	BRFSS: 1 file BRFSS-SMART: County data, MMSA data
HRS	Longitudinal	Black race, Hispanic ethnicity, residents of Florida	Self or proxy reported. Initial interview in-person with telephone follow-up	HRS Core, HRS Exit (data on decedents), HRS Post-Exit (additional financial information on decedents), Supplemental studies
NAMCS	Cross-sectional sample of private practices and nonfederal community health centers	Selected states (2012−2015 only); otherwise, area-based sampling (national, 4 census regions, 9 census divisions)	Paper, electronic (since 2012)	1 file
NHAMCS	Cross-sectional sample of ambulatory care utilization in nonfederal hospital outpatient departments, emergency departments, and ambulatory surgery centers	Selected states (2012−2015 only); otherwise, area-based sampling (national, 4 Census regions, 9 Census Divisions)	Paper, electronic (since 2012)	1 file
NHANES	Cross-sectional sample of civilian, non-institutionalized US population	Hispanic ethnicity (specifically Mexican-American for 1999−2006), Black race, income <130% of federal poverty level; ages 12−19 y (1999−2006), ≥70 y (1997−2006), ≥80 y (2007−present)	In-person, computer-assisted, audio computer-assisted	Demographics, Dietary, Examination, Laboratory, Questionnaire, Limited Access
NHIS	Cross-sectional, household sample of civilian, non-institutionalized households, one adult, and one child from each household sampled for more information	None at household level. Adults aged ≥65 y and Black race, Asian race, and Hispanic ethnicity at adult within household level.	In-person, computer-assisted	Household, Family, Sample Adult/Child, Injury Episode, Adult/Child Alternative Medicine, Adult Cancer, Child Immunization
MEPS	Longitudinal subsample of households participating in NHIS.	None at household level. Adults aged ≥65 y and Black race, Asian race, and Hispanic ethnicity at adult within household level.	Computer-assisted	Household component, insurance component
PSID	Longitudinal cohort, genealogic design (offspring of survey participants are invited to participate)	Low-income families and African American populations. Proportion of oversampling fixed as of 1968, rather than updated each year.	Internet, paper as backup format	Main interview, child development supplement (CDS), transition into adulthood supplement (TAS), disability, and use of time supplement (DUST)

*Currently, all surveys offer sample SAS, SPSS, and Stata code. Historical data prior to the 1990s/early 2000s typically offered sample SAS code or only a PDF documentation manual