Teenage mental health has been a source of growing concern over the past decade, with recent whistleblower testimony pointing to the mental health risks of spending time on social media platforms, especially for girls. This paper investigates the extent to which social media are harmful for teenagers, leveraging rich administrative data from the Canadian province of British Columbia and quasi-experimental variation related to the introduction of wireless internet there. I show neighbourhoods covered by highspeed wireless internet have significantly higher social media use, based on Google search volume data. In the main analysis, I link spatial data on broadband coverage to 20 years of student records that provide detailed information about individual student health. Using this novel data linkage, I estimate a triple-difference model comparing teen girls to teen boys in terms of school-reported mental health diagnoses, before and after visual social media emerged, and across neighbourhoods with and without access to high-speed wireless internet. Estimates indicate high-speed wireless internet significantly increased teen girls’ severe mental health conditions – by 90% – relative to teen boys’ over the period when visual social media became dominant in teenage internet use. I find similar effects across all subgroups. When applying the same strategy, I find null impacts for placebo health conditions – ones for which there is no clear channel for social media to operate. The evidence points to adverse effects of visual social media, in light of large gender gaps in visual social media use and documented risks. In turn, the analysis calls attention to policy interventions that could mitigate the harm to young people due to their online activities.
Since I have written on related questions, normally I would comment here, but when it comes to the job market I feel the candidate and not the blogger should have the last word. Elaine Guo is an excellent and possibly undervalued job candidate, and I hope you employers out there give her absolutely full consideration. Hers is one of the most interesting and most important papers on this job market season.