Scientific background: PHQ-9

About this test

The PHQ-9 was developed by Spitzer, Kroenke, and Williams (1999) based on the DSM-IV criteria for major depression and is one of the most extensively studied screening instruments in clinical psychology and primary care. Numerous studies show good internal consistency (Cronbach's alpha usually above .85) as well as good sensitivity and specificity for detecting depressive disorders. The PHQ-9 is a screening and monitoring tool, not a diagnosis by itself — that always requires a clinical conversation.

Dimensions

Depression severity (total score)

Sum across all nine symptom items (0–27 points).

Sources & license

Kroenke, K., Spitzer, R. L., & Williams, J. B. W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613.
The PHQ-9 is in the public domain and may be reproduced, translated, and used without permission.
https://www.phqscreeners.com

This questionnaire is for self-reflection only and does not replace a medical or psychotherapeutic diagnosis. If your score is in a concerning range, or you're in crisis, please reach out to a doctor, a licensed therapist, or the 988 Suicide & Crisis Lifeline (call or text 988, free and available 24/7 in the US).

How this kind of test is actually built and checked -- in plain language.

What Actually Makes a Test Scientific →Reliability and Validity, Explained Simply →When Is a Screening Result a Reason to Seek Professional Help? →Personality Test vs. Clinical Screening -- What's the Difference? →

Take the test