TitleA Continuous a-Stratification Index for Item Exposure Control in Computerized Adaptive Testing
Publication TypeJournal Article
Year of Publication2018
AuthorsHuebner, A, Wang, C, Daly, B, Pinkelman, C
JournalApplied Psychological Measurement
AbstractThe method of a-stratification aims to reduce item overexposure in computerized adaptive testing, as items that are administered at very high rates may threaten the validity of test scores. In existing methods of a-stratification, the item bank is partitioned into a fixed number of nonoverlapping strata according to the items’a, or discrimination, parameters. This article introduces a continuous a-stratification index which incorporates exposure control into the item selection index itself and thus eliminates the need for fixed discrete strata. The new continuous a-stratification index is compared with existing stratification methods via simulation studies in terms of ability estimation bias, mean squared error, and control of item exposure rates.