The Effect of Speededness on Parameter Estimation in Item Response Theory

Abstract

There is a paucity of research in item response theory (IRT) examining the consequences of violating the implicit assumption of nonspeededness. In this study, test data were simulated systematically under various speeded conditions. The three factors considered in relation to speededness were proportion of test not reached (5%, 10%, and 15%), response to not reached (blank vs. random response), and item ordering (random vs. easy to hard). The effects of these factors on parameter estimation were then examined by comparing the item and ability parameter estimates with the known true parameters. Results indicated that the ability estimation was least affected by speededness in terms of the correlation between true and estimated ability parameters. On the other hand, substantial effects of speededness were observed among item parameter estimates. Recommendations for minimizing the effects of speededness are discussed