The BDI is a self-report questionnaire consisting of 21 items, each designed to assess a specific symptom or attitude related to depression. Respondents rate their experiences over the past two weeks on a scale from 0 to 3, with higher total scores indicating more severe depressive symptoms. The BDI is available in multiple versions, including the original BDI, BDI-IA, and the revised BDI-II.
