Finding salvage in standardization? Structural and longitudinal evaluation of the patient health questionnaire anxiety and depression scale in a UK representative sample.
OBJECTIVES Some research funders mandate the use of the Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) as independent measures of depression and anxiety. This study examined their independence in a UK representative sample by testing the structural validity, external validity, longitu...