CDC/NCHS and Census
July 1 postcensal estimates are available for year 2011 and later; intercensal estimates are available for the years 2001 to 2009; census counts are used for the years 2000 and 2010
Starting in the 2000 decennial census, the U.S Census Bureau has used the 1997 Office of Management and Budget (OMB) revised standards for the classification of Federal data on race and ethnicity. Thus, race data on the 2000 and 2010 census are not comparable with race data from data systems that continue to collect data using the 1977 OMB standards. The 1977 standards specified four single-race categories: American Indian or Alaska Native, Asian or Pacific Islander, black, and white. The 1997 standards required that Federal data collection programs allow respondents to select one or more race categories when responding to a query on their racial identity. This provision means that there are potentially 31 race groups, depending on whether an individual selects one, two, three, four, or all five of the race categories. During the transition to full implementation of the 1997 OMB standards, race data on the 2000 and 2010 censuses were not comparable with race data on other data systems that were continuing to collect data using the 1977 OMB Standards on race and ethnicity. For example, states implemented the revised birth and death certificates, which have race and ethnicity items that are compliant with the 1997 OMB standards, at different times, and for a period of time some states were still collecting race and ethnicity in accordance with the 1977 OMB standards. To meet the need for comparability, the Centers for Disease Control and Prevention, National Center for Health Statistics (CDC, NCHS), in collaboration with the U.S. Census Bureau, developed methodology to bridge the race groups in Census 2000 and 2010 to the four single-race categories specified under the 1977 standards. To provide uniformity and comparability of data for trend comparison, bridged single-race categories are still used for some Healthy People applications.
NCHS released bridged-race population estimates of the July 1st resident population of the United States, based on Census 2000 and 2010 counts, for use in calculating vital rates. Many data systems, such as vital statistics, continued to use the 1977 OMB standards during the transition to full implementation of the 1997 OMB standards. Postcensal population estimates are estimates made for the years following a census, before the next census has been taken. Postcensal estimates are derived by updating the population enumerated in the census using various measures of population change. Each year following the decennial census, the U.S. Census Bureau produces a series of postcensal estimates that includes estimates for the current data year and revised estimates for earlier years. Intercensal population estimates are estimates made for the years between two completed censuses and take into account both censuses. Intercensal estimates replace the postcensal estimates previously made for the time period. The 2001-2009 intercensal estimates were based on both the 2000 and the 2010 decennial census counts and replaced the previous postcensal series of estimates.
U.S. Resident population
The bridging methodology was developed using information from the 1997-2000 National Health Interview Survey (NHIS). The NHIS provides a unique opportunity to investigate multiple-race groups because, since 1982, it has allowed respondents to choose more than one race but has also asked respondents reporting multiple races to choose a primary race. The bridging methodology developed by NCHS involved the application of regression models relating person-level and county-level covariates to the selection of a particular primary race by the multiple-race respondents. Bridging proportions derived from these models were applied by the U.S. Census Bureau to the Census 2000 Modified Race Data Summary file. This application resulted in bridged counts of the April 1, 2000 and April 1, 2010 resident single-race populations for the four racial groups specified in the 1977 OMB standards.
Ingram DD, Parker JD, Schenker N, Weed JA, Hamilton B, Arias E, Madans JH. United States Census 2000 population with bridged race categories. National Center for Health Statistics. Vital Health Stat 2(135). 2003.