The James Q Wilson Factor – Part Deux

It turns out I was not the only person annoyed by Sunday’s James Q. Wilson Op Ed. Texas smart guy, Scott Henson, the public policy wonk who runs the excellent blog, Grits for Breakfast, fulminated mightily over Wilson’s one-sided natterings. Here’s some of what Henson posted on the issue.

For starters, his comment about incarceration vs. safety results in states cannot survive a comparison between Texas and New York, for example, so I’d like to see the research backing up that statement. By relying on Mr. Levitt’s [Freakonomics] often controversial work, he’s identified a scholar whose estimates of the effectiveness of imprisonment fall on the high end of those produced in the last decade. Levitt thinks that imprisonment accounted for as much as 32% of the reduction in crime in the 1990s (See “Understanding why crime fell in the 1990s”).

Other econometric estimates – including one by UT-Austin’s Bill Spelman – found that expanding the prison population accounted for about a quarter of the crime reduction in the ’90s. (Bill and I have enjoyed a friendly dispute about this in the past, because I think some of his assumptions overstate incarceration’s effectiveness and understate its harms). Overall, according to a recent paper by the Vera Institute, Levitt and Spelman “produced a fairly consistent finding, associating a 10 percent higher incarceration rate with a 2 to 4 percent lower crime rate.”

But if we are to be honest about the state of empirical research on the topic, one cannot declare emphatically, as Wilson does, that “deterrence works” or that expanded incarceration “reduces crime.” According to the Vera Institute, “One could use available research to argue that a 10 percent increase in incarceration is associated with no difference in crime rates, a 22 percent lower index crime rate, or a decrease only in the rate of property crime.”

What’s more, even the highest estimates, like Mr. Levitt’s, still contend that 2/3 of the crime 0reduction had nothing to do with incarceration. So the decline in crime, according to these sources, mostly wasn’t because of putting more people in prison.

Wilson says as much when he writes that, “Several scholars have separately estimated that the increase in the size of our prison population has driven down crime rates by 25%.” But crime has declined much more than that since the early ’90s, and Texas’ prison population tripled since then, for example, so if it takes a 300% increase in prison capacity to get a 25% reduction in crime, how far can we really take that strategy?

Wilson similarly ignores research that suggests real, immediate limits to the benefits of incarceration in states that have large prison systems, again from the Vera Institute (p. 7):

Raymond Liedka, Anne Piehl, and Bert Useem have confirmed, moreover, that increases in prison populations in states with already large prison populations have less impact on crime than increases in states with smaller prison populations. States experience “accelerating declining marginal returns, that is, a percent reduction in crime that gets ever smaller with ever larger prison populations,” they argue. Thus, increases in incarceration rates are associated with lower crime rates at low levels of imprisonment, but the size of that association shrinks as incarceration rates get bigger.

There’s more here. Go Scott!