Advances in Record-Linkage Methodology as Applied to Matching the 1985 Census of Tampa, Florida

Abstract A test census of Tampa, Florida and an independent postenumeration survey (PES) were conducted by the U.S. Census Bureau in 1985. The PES was a stratified block sample with heavy emphasis placed on hard-to-count population groups. Matching the individuals in the census to the individuals in the PES is an important aspect of census coverage evaluation and consequently a very important process for any census adjustment operations that might be planned. For such an adjustment to be feasible, record-linkage software had to be developed that could perform matches with a high degree of accuracy and that was based on an underlying mathematical theory. A principal purpose of the PES was to provide an opportunity to evaluate the newly implemented record-linkage system and associated methodology. This article discusses the theoretical and practical issues encountered in conducting the matching operation and presents the results of that operation. A review of the theoretical background of the record-linkage problem provides a framework for discussions of the decision procedure, file blocking, and the independence assumption. The estimation of the parameters required by the decision procedure is an important aspect of the methodology, and the techniques presented provide a practical system that is easily implemented. The matching algorithm (discussed in detail) uses the linear sum assignment model to "pair" the records. The Tampa, Florida, matching methodology is described in the final sections of the article. Included in the discussion are the results of the matching itself, an independent clerical review of the matches and nonmatches, conclusions, problem areas, and future work required. Key Words: Census adjustmentCensus coverage evaluationEM algorithmPostenumeration survey