Calibration of an Item Pool for the Adaptive Measurement of Achievement.

The applicability of item characteristic curve (ICC) theory to a multiple-choice test item pool used to measure achievement is described. The rationale for attempting to use ICC theory in an achievement framework is summarized, and the adequacy for adaptive testing of a classroom achievement test item pool in a college biology class is studied. Using criteria usually applied to ability measurement item pools, the item difficulties and discriminations in this achievement test pool were found to be similar to those used in adaptive testing pools for ability testing. Studies of the dimensionality of the pool indicate that it is primarily unidimensional. Analysis of the item parameters of items administered to two different samples reveals the possibility of a deviation from invariance in the discrimination parameter but a high degree of invariance for the difficulty parameter. The pool as a whole, as well as two subpools, is judged to be adequate for use in adaptive testing. It is also concluded that the ICC model is not inappropriate for application to typical college classroom achievement tests similar to the one studied. (Author)