Yes, that was my angle. And while I share your intuition to some extent, I maintain that it's difficult to get a scientifically sound conclusion without controlling for those variables.
Specifically, to refer to an average of $1,000,000 as a specific effect size, without controlling for the fact that many people with only a high school diploma would not earn more even if they had a college degree, seems suspect.
Specifically, to refer to an average of $1,000,000 as a specific effect size, without controlling for the fact that many people with only a high school diploma would not earn more even if they had a college degree, seems suspect.