Dumb question but can someone explain why we think that (1) education improves intelligence, rather than the alternative conclusion that (2) the intelligent are more inclined to stay in education institutions longer?
I know nobody read the links anymore and react only to the title but, seriously, that’s worrying to not even try when you have a question. Writing the question to ask probably took 10 times more than clicking on the link and reading the first sentence.
Only upon reading the paper do you discover that a "school-age cutoff", much like the famous hockey player study cited by Gladwell in Outliers, is one of the ways for controlling the selection effect I mention.
Since they are controlling for the other effects, that means this analysis doesn't measure them. (Assuming, that is, the controls worked.)