Randomistas: How Radical Researchers Are Changing Our World

by Andrew Leigh

In the United States, the violent crime rate has halved since the early 1990s.4 Meanwhile, the incarceration rate has almost doubled, with nearly 1 per cent of American adults behind bars.5 Black men who do not finish high school have a two in three chance of going to jail at some point in their lives.

‘problem oriented policing’ – an approach in which police work with community leaders to address the underlying causes of crime – may be a more effective form of hot spots policing than strategies that simply focus on arrests.34

if you are confident that a program works, then it is unethical to conduct a randomised trial. But if you are ignorant about whether the program works, and a randomised trial is feasible, Gamoran argues that it is unethical not to conduct one.

If you want to deter crime, focus on certainty, not severity.

‘Most studies estimate the crime-reducing effect of incarceration to be small.’

Prisons are meant to serve four purposes: to rehabilitate inmates, to incapacitate them from harming the community, to make an example of them so as to deter potential wrongdoers, and to exact retribution on behalf of society. But the evidence – including from the California study – increasingly suggests that longer sentences may only serve one of these purposes: retribution. A five-year jail term costs society five times as much as a one-year sentence, but it’s doubtful it has five times the deterrent effect. If the aim is to make society safe, it’s better that we write our laws with thoughtful minds, not angry spleens.