The Patient Health Questionnaire-9 (PHQ-9) is a nine-item self-report screen for the severity of depressive symptoms, mapping directly onto the DSM criteria for a major depressive episode. Each item asks how often, over the past two weeks, the person has been bothered by a given problem.
Used here as an evidence scale: rather than marking a linguistic form, highlight the span where the subject reports the experience an item measures (e.g. loss of interest, low mood, sleep disturbance). Each item is rated on the PHQ-9 frequency anchors (0 = not at all ... 3 = nearly every day). Item 9 (suicidal ideation) flags clinical risk and should be escalated to a clinician regardless of coded severity.