Lies, damned lies, and recidivism statistics

Thanks to this post at Sex Crimes, I see that the Numbers Guy at the Wall Street Journal has this effective post asking the important question "How Likely Are Sex Offenders to Repeat Their Crimes?" and this related print story about the challenges of getting accurate data on sex offender recidivism.  Here are snippets of the blog post from the Numbers Guy:

In debates over laws monitoring released sex offenders, it’s common to hear claims that they’re sure to commit more sex crimes.... But as my print column this week points out, the numbers don’t bear this out.  Recidivism rates vary widely depending on which crimes are counted, the timeframe of the studies, and whether repeat offenses are defined by convictions, arrests, or self-reporting.  But even the author of a widely published report suggesting a recidivism rate of 52%, Wisconsin psychologist Dennis Doren, told me of the notion that all sex criminals are likely to re-offend, “There is no research support for that view, period.” ...

The conventional wisdom on sex-crime recidivism, coupled with high-profile sex crimes against children, has helped spur the spate of registry and neighbor-notification laws, even before they could be properly studied for their impact on recidivism rates. Several researchers, including Dr. Doren, say that residency-restriction laws may be counterproductive. Such a constraint “drives them out of their community, and leads to a lack of stability,” said Karen J. Terry, a criminologist at John Jay College in New York. “Those are some of the underlying conditions that caused them to abuse in the first place.” A consensus on how to measure recidivism, and determine its baseline rate, would help evaluate such laws.

This research is expensive and long-term follow-ups are, by definition, slow to produce results.  Even if we were to know whether rates have declined in recent years, it would be difficult to isolate the cause.  Dr. Doren proposes several alternate explanations for his perception that rates have declined in recent years, including better and more frequent treatment, and closer monitoring.

Critically, the challenging issues spotted by the Numbers Guy attend not only to sex offender recidivism.  The US Sentencing Commission did some very interesting work on recidivism a few years ago (see here and here and here), which found among other things that the recidivism predictor used by the the US Parole Commission two decades ago "is a statistically better recidivism risk prediction instrument than" the criminal history categories incorporated by the Sentencing Commission into the sentencing guidelines.

What's most disconcerting, however, is the common reality that even perfect crime rate studies and data about recidivism cannot alone significantly alter the public viewpoints and political debates.  As we often see in the context of the death penalty, statistical realities and empirical debates often serve —perhaps sometimes just unconsciously —  as cover for the expression of other normative concerns.  Though I sincerely hope lots of smart folks will continue crunching public safety numbers, policy advocates need to invest more time in thinking about how to effectively operationalize solid data insights into sound sentencing reforms.