ERIC Number: ED439156
Record Type: Non-Journal
Publication Date: 2000-Feb
Reference Count: N/A
Effects of Scale Transformation and Test Termination Rule on the Precision of Ability Estimates in CAT. ACT Research Report Series.
Yi, Qing; Wang, Tianyou; Ban, Jae-Chun
Error indices (bias, standard error of estimation, and root mean square error) obtained on different scales of measurement under different test termination rules in a computerized adaptive test (CAT) context were examined. Four ability estimation methods were studied: (1) maximum likelihood estimation (MLE); (2) weighted likelihood estimation (WLE); (3) expected a posteriori (EAP); and (4) maximum a posteriori (MAP). Three measurement scales (theta, number correct score, and American College Test [ACT] score scale) and three test termination rules (fixed length, fixed standard error, and target information) were studied. The findings indicate that the amount and direction of bias, standard error of estimation, and root mean square error obtained under different ability estimation methods are influenced both by measurement scale and by test termination rule in a CAT environment. WLE performed the best among the four ability estimation methods on the ACT score scale with a target information termination rule. (Contains 2 tables, 4 figures, and 21 references.) (Author/SLD)
Descriptors: Ability, Adaptive Testing, Computer Assisted Testing, Error of Measurement, Estimation (Mathematics), Maximum Likelihood Statistics, Scaling, Statistical Bias, Test Length
ACT Research Report Series, P.O. Box 168, Iowa City, IA 52243-0168.
Publication Type: Reports - Evaluative
Education Level: N/A
Authoring Institution: American Coll. Testing Program, Iowa City, IA.