Coverage Error

Coverage error is a bias in a statistic that occurs when the target population does not coincide with the population actually sampled. The source of the coverage error may be an inadequate sampling frame or flaws in the implementation of the data collection. Coverage error results because of undercoverage and overcoverage. Undercoverage occurs when members of the target population are excluded. Overcoverage occurs when units are included erroneously. The net coverage error is the difference between the undercoverage and the overcoverage.