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Highlights

The U.S. Census Bureau conducted the Accuracy and Coverage Evaluation (ACE) survey to estimate the number of people missed, counted more than once, or otherwise improperly counted in the 2000 Census. On the basis of uncertainty in the ACE results, the Bureau's acting director decided that the 2000 Census tabulations should not be adjusted in order to redraw the boundaries of congressional districts or to distribute billions of dollars in federal funding. Although ACE was generally implemented as planned, the Bureau found that it overstated census undercounts because of an error introduced during matching operations and other uncertainties. The Bureau concluded that additional review and analysis of these uncertainties would be needed before the data could be used. Matching more than 1.4 million census and ACE records involved the following four phases, each with its own matching procedures and multiple layers of review: computer matching, clerical matching, field follow-up, and clerical matching. The Bureau applied quality assurance procedures to each phase of person matching. Because the quality assurance procedures had failure rates of less than one percent, the Bureau reported that person matching quality assurance was successful at minimizing errors. Overall, the Bureau carried out person matching as planned, with few procedural deviations. GAO identified areas for improving future ACE efforts, including more complete documentation of computer matching decisions and better assurance that problems do not arise with the bureau's automated systems.

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Recommendations

Recommendations for Executive Action

Agency Affected Recommendation Status
Department of Commerce As the bureau documents its lessons learned from the 2000 Census and continues its planning efforts for 2010, the Secretary of Commerce should direct the bureau to document the criteria and the logic that bureau staff used during computer matching to determine the cutoff scores for matched, possibly matched, and unmatched record pairs.
Closed - Implemented
The documentation associated with the 2000 Census was finalized in June 2002 and was provided to GAO. The documentation addresses the specific and general concerns raised in the report.
Department of Commerce As the bureau documents its lessons learned from the 2000 Census and continues its planning efforts for 2010, the Secretary of Commerce should direct the bureau to examine the bureau's system development and acquisition processes to determine why the problems with A.C.E. computer systems were not discovered prior to deployment of these systems.
Closed - Implemented
The Bureau responded that it planned to review its system development processes to avoid similar problems in the 2010 census. The Bureau has also since formed the Software and Systems 2010 Research and Development Planning Group to define and coordinate 2010 census planning, development, and testing for software processes, information technology systems architecture, and automated data collection.
Department of Commerce As the bureau documents its lessons learned from the 2000 Census and continues its planning efforts for 2010, the Secretary of Commerce should direct the bureau to determine the effect that the printing problems may have had on the quality of data collected for affected records, and thus the accuracy of A.C.E. estimates of the population.
Closed - Not Implemented
When the printing problems were identified, the Census Bureau thought the problems would not significantly affect the coding process. As a result, the Census Bureau did not track the incidence of the problems and cannot report on their impact. However, the Bureau believes their effect on the accuracy of the A.C.E. estimates was minimal because the problems were identified early and corrective procedures were effectively implemented.
Department of Commerce As the bureau documents its lessons learned from the 2000 Census and continues its planning efforts for 2010, the Secretary of Commerce should direct the bureau to determine the effect that the incomplete geocoding section of the questionnaires may have had on the quality of data collected for affected records, and thus the accuracy of A.C.E. estimates of census undercounts.
Closed - Implemented
In September 2004, the Bureau issued a comprehensive evaluation of A.C.E. design and methodology during Census 2000. In this report the Bureau describes why persons would be coded as unresolved: namely, because the follow-up interview did not include the information required to accurately identify this person as a resident of a specific area on Census Day. This report also provides an analysis of the error due to imputation for A.C.E. records with missing data.

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