Why does NCHS use bridged-race population estimates?
Vital rates are based on information obtained from vital records collected through the state-based Vital Statistics Cooperative Program (numerators) and population estimates derived from the U.S. Census (denominators). Because of differences in the timing of implementation of the 1997 standards, beginning with the 2000 data year, the numerators and denominators of vital rates have incompatible race data. The question on race on the 2000 census was based on the revised OMB standards and so allowed respondents to select more than one race category. As a result, population estimates for 2000 and beyond have five single-race categories and up to 26 multiple-race categories. Implementation of the 1997 standards within the Vital Statistics Cooperative System started in 2003, on an individual state basis, and is expected to proceed slowly as states implement revised birth and death certificates which incorporate the revised OMB standards. As of 2008, most states had not revised the race quest
