Is the Beck Depression Inventory reliable over time? An evaluation of multiple test-retest reliability in a...

The Beck Depression Inventory (BDI) is one of the most widely used measures of depression. Many studies have examined the reliability and validity of the BDI. However, we found no published studies that considered the stability of the BDI over multiple administrations (i.e., more than 3 trials), such as is common in clinical trials research and during some clinical interventions. The purpose of this study is to examine the multiple test-retest reliability of the BDI in a presumably nonclinical sample. Results show a 40% decline in BDI scores over 8 weeks, a main effect that accounts for approximately 10% of the variance. We achieved a 40% decrease in self-reported symptoms of depression due to repeated measurement alone, not due to any intervention. This change likely represents measurement error with this instrument rather than any "real" change in depression. The limitations of this study, its implications for research, and its applications to clinical practice are discussed.