Matthew Diemer, Chair of the Combined Program in Education and Psychology (CPEP); Professor, Marsal Family School of Education; Faculty Associate, Institute for Social Research; Professor of Psychology (By Courtesy) with
Nia Holland and Ha Bui, CPEP Graduate Students

Abstract:
This presentation will define and demystify item response theory (IRT) methods, with minimal use of notation and heavy use of visuals. We will explain how IRT methods uniquely estimate (a) how precise items and/or scales are at different levels of the measure of interest, (b) low-information or redundant items that can be streamlined, and (c) optimal scale length, among other advantages for researchers. We will use an R Shiny tool to illustrate IRT concepts, and how IRT methods can be used by psychological researchers to refine measures.