Added Value of Subscores for Tests With Polytomous Items.

Test-takers, policymakers, teachers, and institutions are increasingly demanding that testing programs provide more detailed feedback regarding test performance. As a result, there has been a growing interest in the reporting of subscores that potentially provide such detailed feedback. Haberman developed a method based on classical test theory for determining whether a subscore has added value over the total score. Sinharay conducted a detailed study using both real and simulated data and concluded that it is not common for subscores to have added value according to Haberman's criterion. However, Sinharay almost exclusively dealt with data from tests with only dichotomous items. In this article, we show that it is more common for subscores to have added value in tests with polytomous items.