Kevin Drum finds a new study concerning his favorite hobbyhorse that happens to be covered in lead paint. The key to this study are the two very similar study groups, one of which had an intervention to lower lead levels in the blood, the other not:
Source: Mother Jones
Violent crime arrests go up along with blood lead levels, which should be no surprise at this point. But the final two bars in the chart are the most dramatic. The control and intervention groups, which were very similar to begin with, diverged substantially. The intervention group, even though it probably started out with slightly higher lead levels, was far, far less likely to be arrested for a violent crime in their teenage years compared to the control group. The statistical significance of the drop is extremely strong.
Because the two groups of kids were so similar, there was barely any need for controls. The authors did them anyway (gender, mother’s education, birth weight, etc.), and they had little effect on the final results.
This continues to intrigue. Perhaps George “Machine Gun” Kelly’s nickname should have been Lead Belly.
