The Static-99 and Storytelling

[C.N. Rape, sexual assault, sex offenders, and almost nothing but that.]

The Static-99 is a ten question test intended to determine whether or not a sex offender will reoffend. I’m basically on board with the idea of trying to predict this better than we can get from our guessing/intuition. I did not, however, have high hopes for this Buzzfeed article on the Static-99.  I opened, the article expecting one of those anti-stats, people can do it better than any test, sorts of articles. Not so!

The Buzzfeed article tells a good story—man expectes to get out of prison, is committed to a psychiatric institution based on a predictive test (with the implication that the test is a betrayal of justice)—but I wanted more information:

The Static-99 helps decide which offenders are the riskiest, and looms large over civil commitment proceedings. It weighs a variety of facts about a sex offender’s past in order to predict the likelihood of future offenses.

More precisely, what the Static-99 predicts — with modest accuracy, at best — is the risk that men within a group of sex offenders will commit a new sex offense, compared to other members of that group. Experts agree that it’s a useful tool for managing sex offenders in prison — assessing which of them need higher levels of security, for example. But the way the test is used in civil commitment — to help make high-stakes decisions about offenders’ liberty after they have served their criminal sentences — is highly controversial. [emphasis mine]

You can’t just say it’s modest accuracy! What does that mean? Forgive me, Buzzfeed, but I cannot assume you are writing a statistically literate article. Cat pictures? Nobody compares. Statistical analysis? I’m gonna need some convincing. And—

The value of keeping monsters like Shriner locked away is clear. But few sex offenders are as obviously dangerous as he is. In general, rates of reconviction are low: Only about 5% of sex offenders are convicted of a new sex crime within five years of release.

Right, okay. But it’s also true that in general, it’s hard to prosecute rape and sexual assault. My city pursues criminal charges on roughly 1% of the sexual assault evidence collection kits which are filed. (That would be cases wherein the victim of sexual assault appears at a hospital within 1 or 5 days* of the assault, which is only a small subset of instances of rape.) Buzzfeed, you have so many articles on how hard it is to pursue conviction on rape cases. (Those articles from a fast skim of the last four months) Low re-conviction rates for sex offenders aren’t strong evidence that they’re safe! They might be, but this is not the evidence that will make me believe it. Low re-conviction is the expected outcome where it’s rare to convict at all.

But all of this is not to advocate for the Static-99. When I hear that the current test works like this:

Static-99 scores do not predict the severity of potential future offenses, however. Rapes involving extreme violence and the abuse of young children are lumped together with crimes like voyeurism and indecent exposure.

…I end up a little nervous and a little suspicious

My partner, Jesse, talks about the doing vs. trying distinction. If there’s an action which, when done perfectly, would improve the situation, it is important that in trying to implement it, you’re not screwing everything up. For instance: given the small number of people who can enforce the laws, it might make sense to use data to determine who is more likely to commit a crime, and to use those determinations. Except that it turns out that people are racist and have a lot of biases that are near-impossible to avoid! In attempting to implement a much better system, you could end up creating a new, harder to spot mess.

I support the idea of the Static-99-like test. My impression is that right now, parole hearings and probation decisions could be improved if we used a coin-toss method, and a test that had predictive power about future reoffenses and the severity of said offenses would be excellent. I’m wary of civil commitment, and especially wary of overconfidence given by feeling as though you’ve ‘proved’ that someone is dangerous.

Buzzfeed is telling a story, or a series of them, and I’ll admit, they’re stories that give me a visceral reaction. But the answers I’m drawing, and that I hope readers are drawing, is that this might be a failure of stats and trying.

A Fun or Maybe Terrifying Fact:

“In 1983, the United States Supreme Court decided the landmark case of Barefoot v. Estelle. In this case, the court decided behavioral scientists could competently predict that a specific criminal would engage in future violent behavior “with an acceptable degree of reliability.” What was that acceptable degree of reliability in 1983? About 33%.”



*In things which are shitty for male rape survivors, cis men will (usually) not be able to give physical evidence beyond 24 hours after a rape has occurred. If you are a cis man reading this, I would still suggest going in to a hospital for a kit because exceptions can occur.

2 thoughts on “The Static-99 and Storytelling

  1. +1

    But do you mean, at the end, specifically victims of rape by envelopment? I would have thought that any victim of anal rape would be able to have physical evidence taken for at least as long as a victim of vaginal rape?

    1. Nope! I actually meant rape-by-penetration. For both oral and anal penetration, the evidence is obscured/basically impossible to collect 24 hrs later. Vaginas rarely have stuff going in and out of them at the rate mouths and anuses do, and therefore hold evidence longer.

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