Chetty et al.’s study about the evolution of absolute income mobility in the US since 1940 has received a lot of attention. It purports to show that, since the 1940’s, absolute income mobility has radically decreased in the US. Absolute income mobility is the probability that a person’s income exceeds that of their parents at the same age. Their results are pretty striking and there is probably something going on here, but Vincent Geloso has a nice series of posts about that study, where he makes some important points. In my opinion, his remarks make clear that, even if Chetty et al.’s data are good, the decrease in absolute upward mobility is not as large as what they report.