Calculating multirace categories and race-specific rates: a cautionary note to rural health researchers and analysts.
BACKGROUND
Revised federal standards for racial and ethnic data have resulted in 57 new self-selected multirace categories that cannot be directly compared with traditional "one-race-only" categories. "Bridge methods" are available, but each produces different estimates of single-race populations, raising concern about the potential influence on calculated rates for rural and nonmetropolitan areas.


OBJECTIVE
to examine the potential impact of several bridge methods when calculating race-specific mortality rates.


METHODS
Population and mortality data were collected for 75 counties in Arkansas, and race-specific mortality rates were calculated using 3 deterministic bridging methods: (1) Equal Fractions, (2) Largest Group, and (3) Largest Group Other Than White. The mortality rates were compared at the state and metropolitan/nonmetropolitan levels, as well as for 4 rural substate regions.


RESULTS
Variable rates were obtained from different methods. Estimated mortality rates for the largest single-race groups, White and Black, varied only slightly by method at the state and nonmetropolitan/metropolitan levels. The rural substate regions with the smallest Black populations showed the greatest variation between method-estimated rates for Blacks.


CONCLUSIONS
The results suggest that the smallest minority race categories are exceedingly susceptible to the impact of bridge method selection, especially in nonmetropolitan substate regions.
Hodgson
Todd W
TW
University of Arkansas, Fayetteville 72703, USA. thodgson@uark.edu
Farmer
Frank L
FL
D001131:Arkansas / Q000453:epidemiology; D015340:Epidemiologic Research Design; D005006:Ethnicity / Q000145:classification* / Q000706:statistics & numerical data; D006306:Health Surveys; D006801:Humans; D009026:Mortality; D044469:Racial Groups / Q000145:classification*; D012423:Rural Health / Q000145:classification / Q000706:statistics & numerical data*