I guess there are tons of other confounders possible and quite difficult to control for (admittedly did not read the original study). I guess if you would take

I guess there are tons of other confounders possible and quite difficult to control for (admittedly did not read the original study). I guess if you would take a green space and pour concrete on it just for a study to measure it against a controll, it would for sure also trigger police violence as the protesters will most likely also be quite unhappy.