Psychometric Modeling to Identify Examinees' Strategy Differences during Testing

Aptitude test scores are typically interpreted similarly for examinees with the same overall score. However, research has found evidence of examinee differences in strategies, as well as in the continued application of appropriate procedures during testing. Such differences can impact the correlates of test scores, making similar interpretations for equivalent scores questionable. This study presents some item response theory (IRT) models that are relevant to identifying examinee differences in strategies and understanding of test-taking procedures. First, mixture IRT models that identify latent classes of examinees with different patterns of item responses are considered; these models have long been available but unfortunately are not routinely applied. Strategy differences between the classes can then be studied separately by modeling the response patterns with cognitive complexity variables within each class. Secondly, novel psychometric approaches that leverage response time information (in particular, response time residuals) in order to identify both inter and intraindividual variability in response processes are considered. In doing so, a general method for evaluating threats to validity is proposed. The utility of the approach, in terms of providing more interpretable performance estimates and improving the administration of psychological measurement instruments, is then demonstrated with an empirical example.