01183nas a2200133   4500008004100000245006200041210005900103300001200162490000700174520073400181653003400915100001600949856008400965       2002                        eng d00aAn item response model for characterizing test compromise0 aitem response model for characterizing test compromise  a163-1790 v273 aThis article presents an item response model for characterizing test-compromise that enables the estimation of item-preview and score-gain distributions observed in on-demand high-stakes testing programs. Model parameters and posterior distributions are estimated by Markov Chain Monte Carlo (MCMC) procedures. Results of a simulation study suggest that when at least some of the items taken by a small sample of test takers are known to be secure (uncompromised), the procedure can provide useful summaries of test-compromise and its impact on test scores. The article includes discussions of operational use of the proposed procedure, possible model violations and extensions, and application to computerized adaptive testing. 10acomputerized adaptive testing1 aSegall, D O  uhttp://www.iacat.org/content/item-response-model-characterizing-test-compromise