Estimating the Undocumented Population: A "Grouped Answers" Approach to Surveying Foreign-Born Respondents

As greater numbers of foreign-born persons enter, live, and work in the United States, policymakers need more information--particularly on the undocumented population, its size, characteristics, costs, and contributions. This report reviews the ongoing development of a potential method for obtaining such information: the "grouped answers" approach. In 1998, GAO devised the approach and recommended further study. In response, the Census Bureau tested respondent acceptance and recently reported results. GAO answers four questions. (1) Is the grouped answers approach acceptable for use in a national survey of the foreign-born? (2) What further research may be needed? (3) How large a survey is needed? (4) Are any ongoing surveys appropriate for inserting a grouped answers question series (to avoid the cost of a new survey)? For this study, GAO consulted an independent statistician and other experts, performed test calculations, obtained documents, and interviewed officials and staff at federal agencies. The Census Bureau and DHS agreed with the main findings of this report. DHS agreed that the National Survey of Drug Use and Health is not an appropriate survey for inserting a grouped answers question series.