Summary

An accurate decennial census relies on finding and counting people--only once--in the right place and collecting complete and correct information. GAO reviewed the Department of Commerce's U.S. Census Bureau's (Bureau) plans to (1) improve the census's accuracy--or coverage--with its coverage follow-up operation, (2) assess the accuracy of the census through its census coverage measurement program, and (3) evaluate these efforts after 2010. GAO reviewed documentation and interviewed Bureau officials about the Bureau's coverage follow-up and measurement plans. GAO compared plans for measuring coverage in 2000 and 2010 and interviewed 15 experts about changes to the plans.

The Bureau plans to expand its coverage follow-up operation to improve the accuracy of enumeration data collected in 2010. As in Census 2000, coverage follow-up is intended to resolve count discrepancies (when the number of household members reported on a completed questionnaire fails to match the number of persons for whom information is collected) and complete the enumeration of large households (more than six persons living in a housing unit). For 2010, the Bureau researched new techniques to increase the number of ways a person or household could be selected for coverage follow-up. These include (1) using coverage probes on the census form to identify cases with potential under- or overcount problems, (2) using administrative records to identify households that include persons who may not have been counted, and (3) using computer matching to determine potential duplicate persons. However, it is not clear on what basis the Bureau will select or prioritize cases from this potentially expanded universe. The Bureau plans to further assess the techniques during the 2008 Dress Rehearsal, leaving little time to consider and implement improvements for the 2010 coverage follow-up operation. Because of the potential for the coverage follow-up workload to increase, it will be important for the Bureau to be clear on how it will decide which techniques to use and how it will select coverage follow-up cases to ensure that the operation may best improve coverage. Although the Bureau's overall design for measurement is similar in many respects to the design for 2000, its measurement plan differs in important ways. The Bureau is planning to use a sample design similar to that used in 2000 and still intends to produce net coverage error estimates. However, the Bureau does not plan to use measurement results to adjust the 2010 count of the nation's population and is planning to make four significant changes: (1) conduct the measurement interview 4 months later than it did in 2000, (2) use a different method--logistic regression--to estimate net error, (3) use estimates of the components of coverage error in an effort to improve future decennials, and (4) expand computer matching and clerical matching to match persons in its postenumeration survey to the entire census. Still, the Bureau has not specified when it will produce estimates of net coverage error and the components of coverage error for the 2010 Census. The Bureau also has not clearly described how it will associate the components of coverage error to census operations in order to improve future decennials. Because of the Bureau's changes to its coverage measurement program, it is important for the Bureau to solidify its plans and share them with stakeholders to ensure that there is an agreement on what the program will produce and when the Bureau will produce its results. The Bureau is in the early stages of planning how it will evaluate coverage follow-up and measurement after the 2010 Census. As part of this effort, the Bureau is considering recommendations of the National Academy of Sciences for the Bureau's program of evaluations and experiments for Census 2010. The Bureau has not yet developed a timeline for completing its evaluation plans.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Implemented" or "Not implemented" based on our follow up work.

Recommendations for Executive Action