Data Resource Center Code library

Demographics variables in NHANES 1988-1994, 1999-2000 and 2001-2002

Race/Ethnicity (RIDRETH2)

NCHS has created a variable RIDRETH2 in NHANES 1999-2002 as a bridge variable for Race/Ethnicity.

Data Release
NHANES 1988-1994	NHANES 1999-2002
Variable name
DMARETHN	RIDRETH2
Codes
1=Non-Hispanic white	1=Non-Hispanic white
2=Non-Hispanic black	2=Non-Hispanic black
3=Mexican American	3=Mexican American
4=Other	4=Other Race, including Multi-Racial
	5=Other Hispanic

In the MMWR analysis dataset for NHANES 1988-1994 (nh3mmwr.sas7bdat), DMARETHN is renamed to RIDRETH2. Codes 4 and 5 were not combined, because it is not expected that these “other” categories would be reported, although they would be included in the denominator (so percentages by race/ethnicity may not sum to 1.)

Age in years (RIDAGEYR)

NHANES 1988-1994 used two variables to hold age at screening
HSAGEIR held the digits recorded and HSAGEU holds the units (Months or years).
HSAGEIR includes age in months for children under 1 year of age.
Age is topcoded at 90 years of age.

NHANES 1999-2002 has one variable RIDAGEYR that holds age in years for all respondents.
A separate variable provides age in months for participants under 20 years of age.
Age is topcoded at 85 years of age.

In the program nh3demo.sas, a new age variable is created for age in years in NHANES 1988-1994, using the NHANES 1999-2002 name RIDAGEYR.

Education (DMDEDU)

Data Release
NHANES 1988-1994	NHANES 1999-2002
Variable name
HFA8R	DMD140
Codes
00=never attended or kindergarten only
Number of years attended	1=less than high school
	2=high school or GED
	3=more than high school
88=blank but applicable	7=refused
99=Don’t know	9=don’t know

For both NHANES 1988-1994 and 1999-2002, a variable DMDEDU was created, coding number of years into the same codes used by DMD140.

Poverty Income Ratio

Data Release
NHANES 1988-1994	NHANES 1999-2002
Variable name
DMPPIR	INDFMPIR
Codes
Continuous proportion (1.00=100% poverty)	Continuous proportion topcoded at 5. (1.00=100% poverty)
888888=Blank but applicable	No special codes

For NHANES 1988-1994, a variable INDFMPIR was created, topcoding at 5 as in NHANES 1999-2002.

Grouping variables for poverty income ratio were created for both surveys using INDFMPIR. (PIR6 – six groups, PIR3-three groups, PIR100, PIR200, PIR300, PIR400, PIR500).

PIR3 is consistent with HP2010 groupings (<100, 100-199, 200+), and is used for MMWR analyses. The others are available for exploratory analysis or potentially for DRC quick tables (as per Vargas, Crall, Schneider, 1998).