Coverage measurement has historically served multiple purposes. Since its earliest inception in the 1950 census, it has had the goal of evaluating the accuracy of census counts for geographic and demographic domains, with a focus on assessing net error for domains. The primary goal was to inform users as to the quality of the census counts for various applications. In addition, but to a much lesser extent, coverage measurement has also been used to provide information relevant to developing a better understanding of census process inadequacies, leading to improvements in design for the subsequent census.
The estimation of net error has also raised the possibility of providing alternative counts for use in formal applications, known as census adjustment. We know of only one formal use of adjusted census counts to date, namely, the use of adjusted counts to modify population controls used for the Current Population Survey (CPS), the National Health Interview Survey, the National Crime Victimization Survey, and the Survey of Income and Program Participation during the 1990s, which in turn affected the estimate of the number of people unemployed during the 1990–2000 intercensal period by the Bureau of Labor Statistics. However, the primary focus of coverage measurement in both 1990 and in 2000 was to produce adjusted census counts for official purposes, assuming that it could be demonstrated that the adjusted counts would be preferred to the unadjusted census counts for apportionment and redistricting.
The stated Census Bureau plan that the primary purpose of the coverage measurement program in 2010 would be to measure the components of census coverage error in order to initiate a feedback loop for census process improvement is a substantial innovation. An interesting question is the extent to which a coverage measurement program can be used for this purpose, and a major charge to this panel was to determine the extent to which this new focus of coverage measurement should affect the design of the coverage measurement program and the resulting output and analyses.
Census counts serve a variety of important purposes for the nation, including apportionment, legislative redistricting, fund allocation, governmental planning, and support of many private uses, such as business planning. Users of census data need to know how accurate the counts are in order to determine how well they can support these various applications. The needed information includes an understanding of the extent to which the accuracy of census counts differ by location or by demographic