By now you very likely know about Kevin Drum’s fascinating article arguing that changing levels of childhood exposure to lead explain the massive rise and subsequent decline in U.S. crime rates over the past half-century. …

The argument in the article is that we have an analytical understanding of the link between lead and crime sufficient to justify a $400 billion expenditure to reduce environmental lead. …

So what do you see when you go to the Reyes paper?

She puts forward a regression model that she says is “the best way to determine the relationship between lead exposure in childhood and criminality in adulthood.” This model purports to show a causal relationship between lead exposure and violent crime. But here’s a funny thing about her regression: It also shows no statistically significant relationship between lead exposure and property crime, and no statistically significant relationship between lead exposure and murder. This is extraordinarily counter-intuitive. …

Drum has made clear that his purpose in doing this article was to get further research and attention on the topic. He has succeeded, and I think it a worthy goal. Before reading his article, I had the intuition that lead exposure should have some effect on crime. Reading the article strengthened this belief. I think it should strengthen this belief in any rational person who has not previously seen this evidence. But that is way short of making a convincing case for spending $400 billion of taxpayer money.