berman's nber paper "do working men rebel?", co-authored with joseph felter and jacob n. shapiro, drew the counterintuitive conclusion that reducing unemployment does not reduce insurgency-related violence. in an interview, berman explains the findings as "insurgencies are very small organizations which need very few fighters to keep them going, and are often not constrained by a lack of recruits—and even if they were there’s nothing to stop young men from working by day and planting roadside bombs by night."