A Comparison of Exposure Control Procedures in CAT Systems Based on Different Measurement Models for Testlets

Abstract

This study compared several exposure control procedures for CAT systems based on the three-parameter logistic testlet response theory model (Wang, Bradlow, & Wainer, 2002) and Masters’ (1982) partial credit model when applied to a pool consisting entirely of testlets. The exposure control procedures studied were the modified within .10 logits procedure (Davis & Dodd, 2003), the Sympson-Hetter procedure (Sympson & Hetter, 1985) with a maximum exposure rate restricted to 0.19, the Sympson-Hetter procedure (Sympson & Hetter, 1985) with a maximum exposure rate restricted to 0.29, and maximum information, a no exposure control condition, used as a baseline. The exposure control procedures were evaluated for measurement precision, utilization of the testlet pool, and testlet overlap across test administrations. For both measurement models, the modified within .10 logits procedure provided better pool utilization with little decrement in precision of measurement than either of the Sympson-Hetter procedures.