The U.S. Census Bureau (Bureau) puts forth tremendous effort to conduct a complete and accurate count of the nation's population and housing; yet some degree of error in the form of persons missed, duplicated, or counted in the wrong place is inevitable due to the complexity in counting a large and diverse population. The Bureau designed two operations, Coverage Follow-up (CFU) and Field Verification (FV), to reduce certain types of counting, or coverage, errors in the 2010 Census. GAO was asked to assess (1) the extent to which the Bureau completed CFU and FV on schedule and within estimated cost and (2) the implications of their key design elements for improving coverage. GAO reviewed Bureau evaluations, planning, and other documents on CFU and FV, and prior GAO work, and interviewed Bureau officials.

The Bureau completed CFU and FV on schedule and within budget. FV cost $21 million (about 38 percent less than estimated) and CFU cost about $267 million (about 2 percent less than estimated). These operations followed up on potential errors on census returns or lists of addresses after census data had been initially collected. Their completion provided follow-up data used by subsequent data processing that removed errors from the official census tabulations. Three of the Bureau's key CFU design elements will likely improve overall census accuracy, but their effect on undercounts of different demographic groups is not clear. One key design element increased the number and types of follow-up cases. The Bureau expanded the scope of CFU from about 2 million households in the 2000 Census to more than 7 million in 2010. It also added 20 different types of households for potential follow-up. New types included households that reported members temporarily residing elsewhere, such as at college, in nursing homes, or in jail. According to the Bureau, the 2010 CFU operation should remove more than 2.7 million coverage errors from the census. Another key design element of CFU prioritized follow-up cases based on their likelihood to result in a census correction, which was a reasonable attempt to leverage the resources for the operation. However, the Bureau's evaluation plans, based on considerations of what may best reduce cost or increase accuracy in the future, do not link the demographic characteristics of households to how they responded to the additional questions or CFU results for those households. Therefore, it is unclear whether the prioritized follow-up will help reduce differences in the accuracy of census counts across demographic groups. Finally, CFU's design relied on a telephone-only approach to complete follow-up rather than personal visits. This limited costs, resulting in more follow-up and likely more coverage errors being removed from the census. But the telephone-only decision excluded about 700,000 households from CFU that could not be contacted by telephone. Prior Bureau experience indicates that some historically undercounted groups were less likely to be reachable by telephone, and more recent independent research suggests that trends in telecommunication usage may also make it harder to reach some demographic groups this way in the future. Yet the Bureau's evaluation plans do not include an assessment of either the usefulness of the telephone numbers it collected in reaching specific groups or the effect of these trends. Greater understanding of how best to reach different groups as well as the influence of trends on the effectiveness of CFU could help to control costs while working to further reduce differential undercounts. GAO recommends that the Secretary of Commerce direct the Bureau to assess (1) how well questions to help identify miscounted people on census forms helped reduce differences in the undercounts between demographic groups; (2) the degree to which telephone numbers led to completed contacts for households of various demographic characteristics; and (3) how trends in telecommunication usage and new technology may influence the effectiveness of CFU. The Secretary of Commerce concurred with our recommendations.

Status Legend:

Review Pending-GAO has not yet assessed implementation status.

Open-Actions to satisfy the intent of the recommendation have not been taken or are being planned, or actions that partially satisfy the intent of the recommendation have been taken.

Closed-implemented-Actions that satisfy the intent of the recommendation have been taken.

Closed-not implemented-While the intent of the recommendation has not been satisfied, time or circumstances have rendered the recommendation invalid.

• Review Pending
• Open
• Closed - implemented
• Closed - not implemented

Recommendations for Executive Action

Recommendation: To improve the Bureau's planning for the 2020 Census, and to help the Bureau decide which coverage probes, if any, to use and prioritize for future follow-up efforts, the Secretary of Commerce should require the Director of the U.S. Census Bureau to assess the extent to which historically overcounted and undercounted demographic groups responded to the probes the Bureau followed up on and determine the effectiveness of specific probes in reducing differential undercounts.

Agency Affected: Department of Commerce

Status: Open

Comments: According to the Bureau's 60-day letter response to the report, the Bureau is planning to conduct analysis of the effect of specific probes on hard-to-count responses and counts in the October-December 2011 timeframe. Report expected in January 2012.

Recommendation: To improve the Bureau's planning for the 2020 Census, and to support the Bureau's efforts to control costs while improving census accuracy, the Secretary of Commerce should require the Director of the U.S. Census Bureau to determine the demographic characteristics of the households for which it did and did not obtain telephone numbers and, to the extent feasible, assess the degree to which the telephone numbers were usable and led to completed contacts for households of various follow-up groups and demographic characteristics.

Agency Affected: Department of Commerce

Status: Closed - Implemented

Comments: The Bureau requested additional data from the Decennial Response Integration System contractor to support the recommended analyses. As a result, in August 2011 the Bureau provided us with the results of an assessment of the usability and success of the telephone numbers it used. This commitment to understanding how the Bureau's design of the operation worked to achieve Bureau goals will help the Bureau as it designs more effective operations for 2020 Census.

Recommendation: To improve the Bureau's planning for the 2020 Census, and to ensure that the design of future follow-up efforts is effective in improving census coverage, the Secretary of Commerce should require the Director of the U.S. Census Bureau to assess the implications that trends in landline and wireless usage and other modes of communication and new technology may have both on the design decisions for future CFU-like operations and on their effectiveness in improving census coverage in terms of both overall census accuracy and differential undercounts.

Agency Affected: Department of Commerce

Status: Open

Comments: The Bureau is currently refining the research and testing projects planned for the 2020 Census as well as assessing the 2010 operations and lessons learned during the implementation of those operations. While analysis of trends by the Bureau is likely, the specific analyses to be done, or within which research project, need to be resolved as 2020 research and testing project teams meet and resolve their research designs.