“Haidt cites 476 studies in his book that seem to represent an overwhelming case. But two-thirds of them were published before 2010, or before the period that Haidt focuses on in the book. Only 22 of them have data on either heavy social media use or serious mental issues among adolescents, and none have data on both.
There are a few good studies cited in the book. For example, one co-authored by psychologist Jean Twenge uses a large and carefully selected sample with a high response rate. It employs exploratory data analysis rather than cookbook statistical routines.
Unfortunately for Haidt, that study undercuts his claim. The authors did find that heavy television watchers, video game players, and computer and phone users were less happy. But the similar graphs for these four ways of spending time suggest that the specific activity didn’t matter. This study actually suggests that spending an excessive amount of time in front of any one type of screen is unhealthy—not that there’s anything uniquely dangerous about social media.”