Detecting item memorization in the CAT environment

The purpose of appropriateness/person-fit indices is to identify response p atterns for which a given item response theory model is inappropriate for a n examinee even though that model is appropriate for a group. This study wa s concerned with those cases in which examinees had prior knowledge of item s from an item bank used to generate a computerized adaptive test (CAT) and used the memorized information to inflate their test scores. The objective was to evaluate procedures that could identify these individuals by examin ing the application of person-fit indices in the CAT environment. The l(z) and ECI4(z) indices were selected for comparison. Using information from th ese indices, a new method was developed. All three indices showed little po wer to detect the use of memorization. Some possibilities for altering a te st when the model becomes inappropriate for an examinee are also discussed.