This is what you get when economists try to do medical studies:

Enter Michael Waldman, of Cornell’s Johnson Graduate School of Management. He got to thinking that TV watching — already vaguely associated with ADHD — just might be factor X. That there was no medical research to support the idea didn’t faze him. “I decided the only way it will get done is if I do it,” he says. Waldman and fellow economists Sean Nicholson of Cornell and Nodir Adilov of Indiana University-Purdue were also undeterred by the fact that there are no reliable large-scale data on the viewing habits of kids ages 1 to 3 — the period when symptoms of autism are typically identified. They turned instead to what most scientists would consider wildly indirect measures: cable subscription data (reasoning that as more houses were wired for cable, more young kids were watching) and rainfall patterns (other research has correlated TV viewing with rainy weather).