PHQ-9: One factor or two? - Boothroyd, Luke; Dagnan, David; Muncer, Steven (Psychiatry research, 2019)
Keywords: Adolescent; Adult; Aged; Aged, 80 and over; Depressive Disorder - diagnosis; Factor Analysis, Statistical; Female; Humans; Male; Middle Aged; Patient Health Questionnaire; Psychometrics; Reproducibility of Results; Retrospective Studies; Severity of Illness Index; Young Adult