@article {2312, title = {A Semiparametric Model for Jointly Analyzing Response Times and Accuracy in Computerized Testing}, journal = {Journal of Educational and Behavioral Statistics}, volume = {38}, number = {4}, year = {2013}, pages = {381-417}, abstract = {

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.

}, doi = {10.3102/1076998612461831}, url = {http://jeb.sagepub.com/cgi/content/abstract/38/4/381}, author = {Wang, Chun and Fan, Zhewen and Chang, Hua-Hua and Douglas, Jeffrey A.} } @article {2203, title = {Stratified and Maximum Information Item Selection Procedures in Computer Adaptive Testing}, journal = {Journal of Educational Measurement}, volume = {47}, number = {2}, year = {2010}, pages = {202{\textendash}226}, abstract = {

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.

}, issn = {1745-3984}, doi = {10.1111/j.1745-3984.2010.00109.x}, url = {http://dx.doi.org/10.1111/j.1745-3984.2010.00109.x}, author = {Deng, Hui and Ansley, Timothy and Chang, Hua-Hua} } @article {2152, title = {Severity of Organized Item Theft in Computerized Adaptive Testing: A Simulation Study}, journal = {Applied Psychological Measurement}, volume = {32}, number = {7}, year = {2008}, pages = {543-558}, abstract = {

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\&$\#$39; 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.

}, doi = {10.1177/0146621607311336}, url = {http://apm.sagepub.com/content/32/7/543.abstract}, author = {Qing Yi, and Jinming Zhang, and Chang, Hua-Hua} } @conference {1275, title = {A simulation study to compare CAT strategies for cognitive diagnosis}, booktitle = {Paper presented at the annual meeting of the National Council on Measurement in Education}, year = {2003}, note = {{PDF file, 250 KB}}, address = {Chicago IL}, author = {Xu, X. and Chang, Hua-Hua and Douglas, J.} } @conference {999, title = {Solving complex constraints in a-stratified computerized adaptive testing designs}, booktitle = {Paper presented at the annual meeting of the National Council on Measurement in Education}, year = {2000}, note = {PDF file, 384 K}, address = {New Orleans, USA}, author = {Leung, C-K.. and Chang, Hua-Hua and Hau, K-T.} }