01630nas a2200157 4500008003900000245010100039210006900140300001200209490000700221520111200228100001501340700001601355700001901371700002501390856005701415 2013 d00aA Semiparametric Model for Jointly Analyzing Response Times and Accuracy in Computerized Testing0 aSemiparametric Model for Jointly Analyzing Response Times and Ac a381-4170 v383 a

The item response times (RTs) collected from computerized testing represent an underutilized type of information about items and examinees. In addition to knowing the examinees’ responses to each item, we can investigate the amount of time examinees spend on each item. Current models for RTs mainly focus on parametric models, which have the advantage of conciseness, but may suffer from reduced flexibility to fit real data. We propose a semiparametric approach, specifically, the Cox proportional hazards model with a latent speed covariate to model the RTs, embedded within the hierarchical framework proposed by van der Linden to model the RTs and response accuracy simultaneously. This semiparametric approach combines the flexibility of nonparametric modeling and the brevity and interpretability of the parametric modeling. A Markov chain Monte Carlo method for parameter estimation is given and may be used with sparse data obtained by computerized adaptive testing. Both simulation studies and real data analysis are carried out to demonstrate the applicability of the new model.

1 aWang, Chun1 aFan, Zhewen1 aChang, Hua-Hua1 aDouglas, Jeffrey, A. uhttp://jeb.sagepub.com/cgi/content/abstract/38/4/38101719nas a2200157 4500008003900000022001400039245009400053210006900147300001400216490000700230520121600237100001401453700002001467700001901487856005501506 2010 d a1745-398400aStratified and Maximum Information Item Selection Procedures in Computer Adaptive Testing0 aStratified and Maximum Information Item Selection Procedures in  a202–2260 v473 a

In this study we evaluated and compared three item selection procedures: the maximum Fisher information procedure (F), the a-stratified multistage computer adaptive testing (CAT) (STR), and a refined stratification procedure that allows more items to be selected from the high a strata and fewer items from the low a strata (USTR), along with completely random item selection (RAN). The comparisons were with respect to error variances, reliability of ability estimates and item usage through CATs simulated under nine test conditions of various practical constraints and item selection space. The results showed that F had an apparent precision advantage over STR and USTR under unconstrained item selection, but with very poor item usage. USTR reduced error variances for STR under various conditions, with small compromises in item usage. Compared to F, USTR enhanced item usage while achieving comparable precision in ability estimates; it achieved a precision level similar to F with improved item usage when items were selected under exposure control and with limited item selection space. The results provide implications for choosing an appropriate item selection procedure in applied settings.

1 aDeng, Hui1 aAnsley, Timothy1 aChang, Hua-Hua uhttp://dx.doi.org/10.1111/j.1745-3984.2010.00109.x01559nas a2200145 4500008003900000245009000039210006900129300001200198490000700210520109400217100001201311700001801323700001901341856005301360 2008 d00aSeverity of Organized Item Theft in Computerized Adaptive Testing: A Simulation Study0 aSeverity of Organized Item Theft in Computerized Adaptive Testin a543-5580 v323 a

Criteria had been proposed for assessing the severity of possible test security violations for computerized tests with high-stakes outcomes. However, these criteria resulted from theoretical derivations that assumed uniformly randomized item selection. This study investigated potential damage caused by organized item theft in computerized adaptive testing (CAT) for two realistic item selection methods, maximum item information and a-stratified with content blocking, using the randomized method as a baseline for comparison. Damage caused by organized item theft was evaluated by the number of compromised items each examinee could encounter and the impact of the compromised items on examinees' ability estimates. Severity of test security violation was assessed under self-organized and organized item theft simulation scenarios. Results indicated that though item theft could cause severe damage to CAT with either item selection method, the maximum item information method was more vulnerable to the organized item theft simulation than was the a-stratified method.

1 aQing Yi1 aJinming Zhang1 aChang, Hua-Hua uhttp://apm.sagepub.com/content/32/7/543.abstract00457nas a2200121 4500008004100000245007300041210006900114260001500183100001000198700001900208700001500227856009300242 2003 eng d00aA simulation study to compare CAT strategies for cognitive diagnosis0 asimulation study to compare CAT strategies for cognitive diagnos aChicago IL1 aXu, X1 aChang, Hua-Hua1 aDouglas, J uhttp://www.iacat.org/content/simulation-study-compare-cat-strategies-cognitive-diagnosis00496nas a2200121 4500008004100000245008600041210006900127260002100196100001500217700001900232700001300251856011000264 2000 eng d00aSolving complex constraints in a-stratified computerized adaptive testing designs0 aSolving complex constraints in astratified computerized adaptive aNew Orleans, USA1 aLeung, C-K1 aChang, Hua-Hua1 aHau, K-T uhttp://www.iacat.org/content/solving-complex-constraints-stratified-computerized-adaptive-testing-designs