Method-Toolbox
Sample size estimation in Item Response Theory Although Item Response Theory (IRT) models offer well-established psychometric advantages over traditional scoring methods, they remain underutilized in practice. One reason for this is the challenge meeting the (presumably) larger sample size requirements, especially in complex measurement designs. Accurate a priori sample size estimation is essential for obtaining accurate estimates of item/person parameters, effects, and model fit. As such, it serves as an essential tool for effective study planning, especially in pre-registration and registered reports.