On the factor structure of the Beck Depression Inventory-II: G is the key

The Beck Depression Inventory-II (BDI-II; Beck, Steer, & Brown, 1996) is intended to measure severity of depression, and because items represent a broad range of depressive symptoms, some multidimensionality exists. In recent factor-analytic studies, there has been a debate about whether the BDI-II can be considered as one scale or whether subscales should be distinguished. In the present study, we applied a bifactor model to evaluate the extent to which scores reflect a single variable in a large sample of 1,530 clinical outpatients. We found that total scale score variation reflected some multidimensionality, but not enough to justify the scoring of subscales. We conclude that the BDI-II total scale score reflects a single construct and that reporting and interpreting subscale scores may result in misleading conclusions.