Tyler Cowen said he thinks there is some good evidence that social media are making a significant subset of teenage girls more miserable.

Judge as of 2019-07-18, allowing for the claim's hedge ('some good evidence'). True: by mid-2019 there were credible studies (correlational, longitudinal or experimental, for example Twenge, Kelly et al. 2018 Millennium Cohort, Hunt et al. 2018) linking social media use to worse wellbeing or depression in a meaningful subset of teenage girls, with some causal support. Mostly true: credible studies found such links, mostly correlational, and the causal case was moderate. Mixed: the evidence was roughly balanced, with prominent studies (for example Orben & Przybylski 2019) finding tiny or negligible effects. Mostly false: the evidence then was mostly correlational with small effect sizes, and the claim states as good evidence what was inconclusive. False: the evidence clearly showed no harmful effect on teenage girls.

Set before the research began.

1. E1 Social Media Use and Adolescent Mental Health: Findings From the UK Millennium Cohort Study UCL Discovery (EClinicalMedicine, Kelly, Zilanawala, Booker, Sacker, 2018) · 4 December 2018

   “The magnitude of association between social media use and depressive symptoms was larger for girls than for boys.”

2. E2 Social Media Use and Adolescent Mental Health: Findings From the UK Millennium Cohort Study UCL Discovery (EClinicalMedicine, Kelly, Zilanawala, Booker, Sacker, 2018) · 4 December 2018

   “Multivariate regression and path models were used to examine associations between social media use and depressive symptoms.”

3. E3 The association between adolescent well-being and digital technology use - Nature Human Behaviour Nature Human Behaviour (Orben & Przybylski) · 14 January 2019

   “The association we find between digital technology use and adolescent well-being is negative but small, explaining at most 0.4% of the variation in well-being.”

The 2018 Millennium Cohort Study by Kelly et al. (E1, E2) used regression and path models to examine links between social media use and depressive symptoms in adolescents. It found that the link was larger for girls than for boys. That supports the claim's focus on teenage girls, but the quoted method shows association, not causation. Orben & Przybylski (E3), published in January 2019, found the link between digital technology use and adolescent well-being to be negative but small, explaining at most 0.4% of the variation. The criteria name this as the marker of a roughly balanced, mixed body of evidence, and none of the cited evidence shows causal support, even allowing for the claim's hedge.