> People who go to college have higher lifetime incomes that folks that don't. A flawed comparison, though. Nobody was ever expecting the academic superstar, w

> People who go to college have higher lifetime incomes that folks that don't. A flawed comparison, though. Nobody was ever expecting the academic superstar, who breezed his way through college, to make the same or less than someone who suffers from crippling down syndrome, who was rejected by college admissions. Clearly people exist on a spectrum. Some people are much more capable than others and the marketplace will pay more for those who are more capable. Contrary to popular belief, down syndrome is established in the womb, not caused by not going to college. What we really want to know is if the same person will realize a higher lifetime income by going to college verses not. That's impossible to determine experimentally, but what we can do is observe people on the spectrum over time. Within a sufficiently large population, the spectrum will remain continuous even as individuals come and go. Unfortunately, when we do that we find that incomes have held stagnant. The matching person of the past without a college degree made the same amount of money as the equivalent person today with a degree. This means that college does not provide an income boost. The selection bias you point out is real, but doesn't provide anything useful other than to remind us that correlation does not imply causation.