Sometimes we think things have been incontrovertibly been proven, but we really only know them. Other times we think we know them but we really only think them. It’s always interesting when we something we think becomes something we know. We share those beliefs a little more often with a little more confidence. We start trying to tilt the balance of common knowledge one conversation at a time. I’d argue, however, that we would often be better served to wait until something is proven, as much as something can be proven. Or, at the very least, that our conversational was weight shifted far more when truly compelling evidence hits the scene.
I already believed that New York City’s infamous “Stop and Frisk” program was bad. That the bad outweighed the good. I was always careful to soften my language, to hedge my claims, however, because I always suspected there had to be some margins on which the program yielded some benefit to someone, somewhere, in some context. Criminal deterrence is real, after all.
I no longer feel any need to soften my language or claims one iota. There are research papers that change your priors. There are also ones that harden them into granite. Jonathan Tebes and Jeffrey Fagan have a new working paper they are presenting at conferences and quietly circulating that provides the single most compelling research effort into the effects of Stop and Frisk I have come across to date, one which makes the case that Stop and Frisk had now measurable effect at the margin to deter crime while, at the same came, causing significant harm to the young Black men walking the streets of New York City.
Please go through the slides, but let me summarize. Using a credible and clever event study design around the end of Stop and Frisk, Tebes and Fagan are able to identify the effect of stops on crime, finding an impressively precise null effect. They then look the effect of these stops of neighborhood schooling outcomes, specifically interruptions to instruction, persistent absences, suspensions, and graduation. The result, again, is very clear: Stop and Frisk was a disaster for high school age Black Men.
I’m just going to leave it there. Read the slides, read the paper when they release it, update your priors. And when someone tries to tell you at Thanksgiving dinner this year that New York City is going straight to hell because they ended Stop and Frisk, have the confidence to vigorously attempt to update their priors. Will it work? I’ve never met your family…but probably not.
But you gotta try, right? It’s your duty. And then make yourself a drink or take an extra slice of pie knowing that you earned it.
Economist Writing Every Day 