Scale Overview & Construct
9-item depression screening tool measuring symptom severity over the past 2 weeks. Scores range from 0 to 27.
Purpose & Measurement Objectives
Instrument Specifications
Scientific Documentation & Psychometric Rigor
Internal Consistency & Reliability
Original validation study reported high internal consistency (Cronbach's alpha = .89).
Construct & Criterion Validity
Extensively validated against structured clinical interviews; one of the most widely used depression screening tools worldwide.
Academic Citations
Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606-613.
Academic Citation & Instrument Provenance
When referencing this instrument in research, academic theses, or clinical institutional audits, please cite the original author publication:
Governance, Boundaries & Ethical Use
Imported from the OpenScales open item-bank project. This specific digital implementation has not been independently clinically validated by PsiQ — scores are for self-reflection, research, and educational purposes only, and are not a diagnosis.
License: Pfizer released all PHQ and GAD-7 screeners without copyright restriction (https://www.phqscreeners.com/); this OpenScales digital implementation is licensed CC BY 4.0. Citation: Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613. This is not a diagnostic tool. If you are in crisis or having thoughts of self-harm, please contact a licensed mental health professional or a crisis helpline in your country immediately.