How accurately ability is estimated when the test model does not fit the data is considered. To address this question, this study investigated the accuracy of the maximum likelihood estimator of ability for the one-, two- and three-parameter logistic (PL) models. The models were fitted into generated item characteristic curves derived from the…

Measurement disturbances, such as guessing, startup, and plodding, often result in an examinee's ability being either over- or under-estimated by the maximum likelihood estimation employed in latent trait psychometric models. Several authors have suggested methods to lessen the impact of unexpected responses on the ability estimation process. This…

This paper brings to first fruition an analytic schema based on four elements which involve a conception of skills independent or particular testing devices: (1) the development and application of a class of statistical models incorporating qualitative definitions of skill, distorted in item response by errors conceived as misclassifications; (2)…