Assessing test-retest reliability of psychological measures: persistent methodological problems

Abstract

Psychological research and clinical practice rely heavily on psychometric testing for measuring psychological constructs that represent symptoms of psychopathology, individual difference characteristics, or cognitive profiles. Test-retest reliability assessment is crucial in the development of psychometric tools, helping to ensure that measurement variation is due to replicable differences between people regardless of time, target behavior, or user profile. While psychological studies testing the reliability of measurement tools are pervasive in the literature, many still discuss and assess this form of reliability inappropriately with regard to the specified aims of the study or the intended use of the tool. The current paper outlines important factors to consider in test-retest reliability analyses, common errors, and some initial methods for conducting and reporting reliability analyses to avoid such errors. The paper aims to highlight a persistently problematic area in psychological assessment, to illustrate the real-world impact that these problems can have on measurement validity, and to offer relatively simple methods for improving the validity and practical use of reliability statistics.