A comparison of three linear equating methods for the common-item nonequivalent-populations design

Abstract

Three linear equating methods for the common-item nonequivalent-populations design are compared using an analytical method. The analysis investigated the behavior of the three methods when the true-score correlation between the test and anchor was less than unity, a situation that may occur in practice. The analysis is graphically illustrated using data from a test equating situation. Conclusions derived from the analysis have implications for the practical application of these equating methods. Index terms: congeneric model, Levine equating method, linear equating, Tucker equating method.