Choosing Between Cronbach’s Coefficient Alpha, McDonald’s Coefficient Omega, and Coefficient H: Confidence Intervals and the Advantages and Drawbacks of Interpretive Guidelines

Abstract

The purpose of this instructional piece was to provide a nontechnical synthesis of common internal consistency reliability estimates used in professional counseling and in related fields. The article begins with an overview of coefficients alpha, omega, omega hierarchical, and H, with guidelines for their selection. Next, I provide recommendations for interpretive cutoff scores for higher and lower stakes testing followed by commentary on the limitations of relying too heavily on such guidelines. I discuss the importance of reporting confidence intervals (CIs) for reliability estimates to enhance reliability generalizations. When evaluating internal consistency reliability estimates of scores based on sample data counselors are advised to (a) determine the intended use of test scores in terms of higher or lower stakes testing, (b) take a multifaceted approach and consider the requirements of each reliability index, (c) include CIs, and (d) refer to interpretive cutoff scores as tentative general guidelines, not absolute standards.

Keywords:

• Internal consistency reliability
• confidence intervals for reliability
• Cronbach’s coefficient alpha
• composite reliability estimates
• McDonald’s coefficient omega

Disclosure Statement

No potential conflict of interest was reported by the author.

Additional information

Notes on contributors

Michael T. Kalkbrenner

Michael T. Kalkbrenner is a Full Professor of Counseling and Educational Psychology and the director of the Clinical Mental Health Counseling Program at New Mexico State University.