Frontline takes on the NFL over concussions.

Knowing what we do about the brain, it’s hard to imagine that repeated traumatic impacts to the head wouldn’t have some negative effect over time.  And it’s obviously not hard to imagine that the NFL would go to extreme lengths to avoid admitting this, given the money involved.

But the rigor of the reporting isn’t quite what you’d expect from Frontline.  For one thing, they don’t even bring up the problems with correlation.  In other words, just because NFL players suffer from chronic traumatic encephalopathy (CTE), it doesn’t mean that playing in the NFL caused the disease.

Of course, it’s reasonable to think that it might have.

But NFL players are the definition of a non-random sample, extreme in almost every sense of the word.  What if higher levels of testosterone cause CTE?  Or use of PEDs?  Or forced retirement in your mid-30’s?  Or some other trait that many NFLers share?

I don’t know how you do this story without raising that issue.