ment program (7–B). Finally, we discuss the use of administrative records, the focus of a major experiment in 2000 (7–C).


The quality of census coverage and the possibility of statistically adjusting census totals to reflect coverage gaps developed into the defining issues of the 1990 and, especially, the 2000 censuses. That some people are missed in the census count while others may be multiply counted is virtually inevitable and has never been in dispute, even since the earliest censuses. However, the intensity of the political debate over census coverage, over the differential nature of census undercount by race and other demographic groups, and over the reliability and validity of statistical adjustment grew enormously in the past two censuses, to the point that the 2000 census was conducted under an unprecedented level of oversight and suspicion.

The results of 2000 coverage evaluation efforts have not settled the ongoing debate over census adjustment. In the 2000 census cycle, the Census Bureau faced three separate points at which a decision on statistical adjustment had to be rendered: March 2001 for redistricting purposes, October 2001 for federal fund allocation and other purposes, and March 2003 for use as the base for postcensal population estimates. In all three instances, the Bureau opted against adjustment as results of the Accuracy and Coverage Evaluation (ACE) Program—the followup survey used to assess census coverage and derive adjustment factors—showed unanticipated results. In March 2001, concern over the discrepancy between ACE-adjusted census counts and the alternative population count derived through demographic analysis was sufficiently large to deter adjustment; ACE research through October 2001 resolved some conceptual issues and led to a significantly lower estimate of national net undercount in the census, but still left too many unanswered questions for the Bureau to recommend adjustment. By March 2003, Bureau reexamination of the ACE (ACE Revision II, in their terminology) suggested a national net overcount of population, the first such finding in census history (although different racial and demographic groups still experienced significant net undercount at the national level).

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