I think the paper that I looked at was The Answer is Lead Poisoning. Mainly just looking at the graphs & tables.
The city size pattern is not a unique prediction of the lead hypothesis (there are various other differences between large & small cities which could account for it, though nothing that strikes me as overwhelmingly obvious), but it is a relatively unambiguous prediction (especially if there’s high quality data on city size vs. environmental lead levels—I’m not sure how good those data are). If large vs. small cities turned out not to have this difference in crime trends then that would be pretty strong evidence against the lead hypothesis, so the fact that the comparison did come out this way must be at least some evidence in favor of the lead hypothesis.
I think the paper that I looked at was The Answer is Lead Poisoning. Mainly just looking at the graphs & tables.
The city size pattern is not a unique prediction of the lead hypothesis (there are various other differences between large & small cities which could account for it, though nothing that strikes me as overwhelmingly obvious), but it is a relatively unambiguous prediction (especially if there’s high quality data on city size vs. environmental lead levels—I’m not sure how good those data are). If large vs. small cities turned out not to have this difference in crime trends then that would be pretty strong evidence against the lead hypothesis, so the fact that the comparison did come out this way must be at least some evidence in favor of the lead hypothesis.