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Podcast: When Data Tells Us To Lock Someone Up

“We talk a lot about the statistics in these tools, but at the end of the day, these still end up being policy questions. Even a perfect statistical tool might say I have a 50 percent chance of committing a crime. Whether you think that’s a high risk or a low risk — that’s a policy decision.” — Ben Casselman


Can we measure the likelihood that someone who has committed a crime will do so again? Statistical tools being used in different parts of the criminal justice system are trying to do just that. These tools, known as risk assessments, can help decide whether someone needs social services or should get parole, and the tools are now being used, among other things, in sentencing decisions. If an assessment predicts that someone who has committed one crime is more likely to commit another, we may jail them for longer. But does this mean we might start locking people up for crimes they haven’t yet committed?

On this week’s episode of our podcast What’s The Point, we take a look at the intersection of data and criminal justice with Ben Casselman of FiveThirtyEight and Dana Goldstein of The Marshall Project. Along with FiveThirtyEight’s Anna Maria Barry-Jester, they recently collaborated on an in-depth look at the use of risk assessment.

Plus, this week’s Significant Digit: Spam accounts for 49.7 percent of all emails sent — which is actually a 10-year low.

Stream or download the full episode above, and find a video excerpt — in which we analyze one of the risk assessment scoring sheets — below.

What’s the Point: Data and prison sentencing

How do we measure a risk assessment’s effect?

Excerpt from Ben Casselman, Dana Goldstein and Anna Maria Barry-Jester’s article. Read the full piece here.

Determining other impacts of risk assessment is even harder. Jennifer Skeem, a University of California, Berkeley, psychologist who has written extensively on risk assessment, said there simply isn’t enough data available to say with certainty whether it reduces racial disparities in the justice system. But she said better data alone won’t be enough to resolve the questions the tools raise.

“I’m not convinced that when we do have the evidence, that it’s going to shut down the debate” because there will still be more fundamental questions, she said.

The core questions around risk assessment aren’t about data. They are about what the goals of criminal justice reforms should be. Some supporters see reducing incarceration as the primary goal; others want to focus on reducing recidivism; still others want to eliminate racial disparities. Risk assessments have drawn widespread support in part because, as long as they remain in the realm of the theoretical, they can accomplish all those goals. But once they enter the real world, there are usually trade-offs.

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What’s The Point’s music was composed by Hrishikesh Hirway, host of the “Song Exploder” podcast. Download our theme music.

Jody Avirgan hosts and produces podcasts for FiveThirtyEight.