Overcoverage in the 2011 Canadian Census

The Census Overcoverage Study (COS) is a critical post-census coverage measurement study. Its main objective is to produce estimates of the number of people erroneously enumerated, by province and territory, study the characteristics of individuals counted multiple times and identify possible reasons for the errors. The COS is based on the sampling and clerical review of groups of connected records that are built by linking the census response database to an administrative frame, and to itself. In this paper we describe the new 2011 COS methodology. This methodology has incorporated numerous improvements including a greater use of probabilistic record-linkage, the estimation of linking parameters with an Expectation-Maximization (E-M) algorithm, and the efficient use of household information to detect more overcoverage cases.