Assessing the Reliability of Beck Depression Inventory Scores: Reliability Generalization across Studies

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Abstract
The reliability estimates for the Beck Depression Inventory (BDI) scores across studies were accumulated and summarized in a meta-analysis. Only 7.5% of the articles reviewed reported meaningful reliability estimates, indicating that the logic of “test score reliability” generally has not prevailed in clinical psychology regarding application of BDI. Analyses revealed that for BDI, the measurement error due to time sampling as captured by test-retest reliability estimate is considerably larger than the measurement error due to item heterogeneity and content sampling as captured by internal consistency reliability estimate. Also, reliability estimates involving substance addicts were consistently lower than reliability estimates involving normal subjects, possibly due to restriction of range problems. Correlation analyses revealed that standard errors of measurement (SEMs) were not correlated with reliability estimates but were substantially related to standard deviations of BDI scores, suggesting that SEMs should be considered in addition to reliability estimates when interpreting individual BDI scores.