Due to scheduled system maintenance, LSAC customer service representatives will be available only from 8:30 a.m. to 5 p.m. ET on Thursday, March 27. We will return to our normal schedule, 8:30 a.m. to 8 p.m. ET, on Friday, March 28.

Test Process Data

Derivation and Applicability of Asymptotic Results for Multiple-Subtest Person-Fit Statistics (RR 15-02)

by Casper J. Albers, Rob R. Meijer, and Jorge N. Tendeiro, University of Groningen, Groningen, the Netherlands

In high-stakes testing, it is important to verify the validity of individual test scores. Although a test, in general, results in valid test scores for most test takers, there may be individual test takers with unusual answer patterns for whom test score validity is questionable. One example of such aberrance is a test taker who guesses on a large number of questions or one who has preknowledge of the answers to some questions. An effective statistical technique (developed for a single test) was extended for tests that consist of multiple subtests, as does the Law School Admission Test. The results of simulation studies indicated that this extension was useful in categorizing test score patterns as normal or aberrant, even when subtests have only 10 items.

Back to report gallery

Request the full report

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.

Read More

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.

Read More