One of those infamous recent “studies” found that 88% of America’s leading criminologists do not believe the death penalty is an effective deterrent to crime.
I use scare quotes because virtually all such “studies” are commissioned by one side or another of a major public policy divide. The questions asked are rarely framed in neutral language. The expertise of those consulted frequently turns out to be unrelated to the area of study about which the inquiries are made. Such data as may result is rarely presented scientifically and impartially.
I take them all with a truckload of salt. Most “studies” are simply propaganda exercises.