Tools better at screening for low risk than pinpointing high risk
The team of Seena Fazel and Jay Singh are at it again, bringing us yet another gigantic review of studies on the accuracy of the most widely used instruments for assessing risk of violence and sexual recidivism.
This time, the prolific researchers -- joined by statistician Helen Doll and professor Martin Grann -- report on a total of 73 research samples comprising 24,847 people from 13 countries. Cumulatively, the samples had a high base rate of reoffense, with almost one in four reoffending over an average of about four years.
Bottom line: Risk assessment instruments are fairly good at identifying low risk individuals, but their high rates of false positives -- people falsely flagged as recidivists -- make them inappropriate “as sole determinants of detention, sentencing, and release.”
In all, about four out of ten of those individuals judged to be at moderate to high risk of future violence went on to violently offend. Prediction of sexual reoffense was even poorer, with less than one out of four of those judged to be at moderate to high risk going on to sexually offend. In samples with lower base rates, the researchers pointed out, predictive accuracy will be even poorer. ..For the rest of this story: by In the News, Karen Franklin
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