Test Process Data

Likelihood-based Estimation Methods for Models for Concurrent Continuous and Discrete Responses (RR 05-04)

Test theory typically deals with categorical responses to test questions (items), for instance, correct/incorrect responses or responses that represent a choice from a finite number of alternatives. Whenever technically possible, it is attractive to collect information on continuous response variables that accompany these responses as a covariate. One obvious example is response time; other examples are information on cursor movement in computer-based testing, eye-tracking information, or physiological information.

In the present report, an item response theory (IRT) model (recall that IRT is a mathematical model that is typically used to analyze test data) is proposed that allows for the simultaneous analysis of categorical and continuous data within a testing situation. To make the model general, we deal with the case of multidimensional abilities as well as items that are presented in testlets (e.g., sets of items that are based on a common text passage).

A method for estimating the necessary parameters for the proposed model is presented and statistical tests of model fit are evaluated. The false positive error rates of the model fit tests were shown to be low, and decreased as sample size and test length were increased. The power of the tests to detect true model misfit decreased as the complexity of the IRT model increased.

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Additional reports in this collection

The Bayesian Covariance Structure Model for Testlets...

Standard item response theory (IRT) models have been extended with testlet effects to account for the nesting of items; these are well known as (Bayesian) testlet models or random effect models for testlets. The testlet modeling framework has several disadvantages. A sufficient number of testlet items are needed to estimate testlet effects, and a sufficient number of individuals are needed to estimate testlet variance. The prior for the testlet variance parameter can only represent a positive association among testlet items.

Modeling Multilevel Dependence Structures for Responses...

Bayesian covariance structure modeling (BCSM) offers a flexible approach to modeling complex interdependences that arise when gathering test-taker data through computerized testing. In addition to the scored responses, process data such as response times or action patterns are obtained. Data from different sources may be cross-correlated; furthermore, within each data source, blocks of correlated observations may form testlet structures. In previous reports, BCSM was limited to the assumption that all test takers are part of the same group.