The Reliability, But Not the Cronbach’s Alpha, of Knowledge Tests Matters: Response to Zitzmann and Orona (2025)

Abstract

In their commentary on our meta-analysis, Zitzmann and Orona (2025) used formal proof and cited methodological studies to argue that test reliability is important, Cronbach’s Alpha generally indicates test reliability, and cutoff values for alpha are indispensable. We agree that high reliability is important for all tests. Yet, alpha does not reflect the reliability of knowledge tests. Zitzmann and Orona’s arguments are based on the unwarranted assumption that knowledge is always homogeneous. Using a concrete example, we show how item interrelatedness (i.e., alpha) can be low for heterogeneous constructs such as knowledge, even when measurement error is minimal (i.e., reliability is high). After a brief discussion of how researchers can heuristically assess construct heterogeneity, we explore alternatives to alpha for evaluating the reliability of knowledge tests. We conclude that abandoning alpha as a reliability index does not compromise the quality of measurement. On the contrary, it is a step toward sounder methodological standards in the measurement of knowledge.