A quadratic curve test equating method for equating different test forms under a random-groups data collection design is proposed that equates the first three central moments of the test forms. When applied to real test data, the method performs as well as other equating methods. Procedures from implementing the test are described. (SLD)

Item-preequating and random groups designs were used to equate forms of the American College Testing Assessment Mathematics Test for over 36,000 students. Equipercentile and three-parameter logistic model item response theory (IRT) procedures were used for both designs. The pretest methods did not compare well with the random groups method. (SLD)

In this paper a quadratic curve equating method for different test forms under a random-group data-collection design is proposed. Procedures for implementing this method and related issues are described and discussed. The quadratic-curve method was evaluated with real test data (from two 30-item subtests for a professional licensure examination…