Evaluating continuous measurement: data quality in the Bronx test site of the American community survey

The American Community Survey (ACS) is a continuous measurement survey program designed to replace the census long form sample. While the census sample provides detailed socioeconomic data once a decade, the ACS will provide these data annually using a questionnaire that largely mirrors the census long form. This paper examines operational data in Bronx County, one of 36 ACS test counties, and finds the ACS superior to the census on two important measures of data quality. First, applying the minimal data requirement for inclusion of a long form in the census sample, ACS questionnaires were significantly more likely than the long forms to meet this threshold. Second, the level of nonresponse to items on the ACS was often one-half the census level. The ACS and census have sharply divergent goals and operational methods that affect data quality. The primary objective of the census is a population count for reapportionment and redistricting; collecting long form information is a secondary goal. In contrast, the primary objective of the ACS is to estimate the characteristics of an area based on answers to all items on the survey. Operationally, the census follows up every nonresponding household, using a pool of minimally trained, temporary workers. In comparison, the ACS follows up only one-in-three nonresponding households, using a permanent cadre of professional interviewers. This results in superior nonresponse follow-up in the ACS, with lower levels of non-sampling error, even in more difficult-to-enumerate high poverty areas of the Bronx. The ACS is to be fully implemented in July 2004, pending Congressional funding. With detailed socioeconomic data available annually from the ACS, the 2010 census would then be able to focus primarily on a population headcount. The paper concludes by discussing operational aspects of the ACS that must be improved, including increasing its visibility, for the survey to he accepted as an integral part of the nation's data collection system.