AUC (Area Under the ROC Curve)
Definition
The standard metric for risk-instrument predictive accuracy: a value of 0.50 equals chance; 0.70 is typically described as moderate accuracy; 1.00 is perfect discrimination. Most forensic risk instruments achieve AUC values between 0.65 and 0.75 for violence prediction.
- Chance level
- 0.50
- Perfect discrimination
- 1.00
- Moderate accuracy
- Around 0.70
- Typical forensic range
- 0.65 to 0.75 for violence prediction
- Field
- Forensic risk assessment
Common questions
What does an AUC of 0.70 actually mean when comparing two risk instruments?+
It means that if you randomly pick one person who reoffended and one who did not, the instrument correctly ranks the reoffender as higher risk about 70 percent of the time. It reflects ranking accuracy across the whole sample rather than accuracy at any single risk cutoff score.
Why do most forensic risk instruments cluster in the 0.65 to 0.75 AUC range rather than higher?+
Violence and reoffending are influenced by many situational and dynamic factors that a fixed set of static and clinical items cannot fully capture, so even well-validated instruments leave meaningful unexplained variance, which caps their ranking accuracy well short of 1.00.
Related terms
- BSA 2023 § 39
- Section 39 of the Bharatiya Sakshya Adhiniyam 2023, the provision governing expert opinion evidence in Indian courts. Replaced Indian Evidence Act 1872...
- HCR-20 V3
- The Historical Clinical Risk Management-20, Version 3 (2013): 20-item SPJ instrument covering Historical, Clinical, and Risk Management domains, producing a Low/Moderate/High risk...
- SAPROF
- Structured Assessment of Protective Factors for Violence Risk (2009): 17-item SPJ instrument covering internal, motivational, and external protective factors; used alongside HCR-20...
- SARA
- Spousal Assault Risk Assessment Guide (1994, updated 2008): 20-item SPJ tool specifically developed for intimate partner violence risk assessment, producing Low/Moderate/High categorical...
- Structured Professional Judgement (SPJ)
- A risk-assessment paradigm in which a clinician codes empirically supported risk factors on a defined scale and then makes a professional judgement...
- VRAG-R
- Violence Risk Appraisal Guide-Revised (2015): 12-item fully actuarial instrument whose score places an individual in one of nine bins, each associated with...