An Effect-Size Comparison of the Beck, Zung, and Hamilton Rating Scales for Depression: A Three-Week and Twelve-Week Analysis

Three widely used measures of depression, the Beck Depression Inventory, Zung Self-rating Depression Scale, and Hamilton Rating Scale for Depression, were used in an analysis of treatment effects over time. Results were not consistent with those of an earlier meta-analysis of Lambert, Hatch, Kingston, and Edwards in 1986. Present findings indicate that the Zung's self-rating is more likely to show early treatment gains while Beck's inventory shows larger gains over a longer time. Scores on the Hamilton Rating fall between the other two. These results indicate that research should be focused on the differences among these scales.