Clarifying the Effect of Test Speededness

In the context of high-stakes tests, test takers who do not have enough time to complete a test rush toward the end and may engage in speeded behavior when tests do not penalize guessing. Using mathematical derivations and simulations, previous research showed that random guessing responses should attenuate interitem correlations, and therefore, decrease estimates of reliability. Meanwhile, other researchers showed that random guessing could in fact inflate reliability estimates using real data. We provide analytical derivations on how speededness could affect correlations between two dichotomous items in multiple ways, depending on the manifestation and prevalence of test speededness. Furthermore, we provide two simulation studies that evaluate the magnitude of impact of test speededness on interitem correlations and Cronbach's alpha. We found that the impact of test speededness can vary between item pairs and that it depends on the manifestation of test speededness and item level characteristics. Furthermore, speeded responses will, in general, attenuate or not affect reliability estimates, depending on the prevalence of such responses and conceptual interpretation of speeded responses. Implications of the findings are discussed.