09/06/2026
Amid the back-to-school shopping and lunch preparations, another familiar routine is unfolding: the tedious and endless battle over smartphone use.
But for all the angst, no one can say with confidence what strategies work. That uncertainty is what Stanford economist Matthew Gentzkow hopes to change.
Gentzkow, faculty director of Stanford Impact Labs, is launching one of the first large-scale randomized studies of phone-use policies for children ages 9 to 14. His team will work with the Utah governor’s office and Qustodio, a software company building internet safety solutions for families, to test different strategies for managing phone use.
“The stakes couldn’t be higher,” Gentzkow says. “We don’t know for sure how much of the deterioration in youth mental health is due to smartphones. But if there’s even a 25 percent chance that it’s responsible, that’s hugely important for the world. On top of that, there are low-probability but very serious risks—impacts on eating disorders, suicides, sexual exploitation, and more.”
Over the past decade, youth mental health has plummeted while smartphones have become nearly universal. Families and schools are improvising rules—phone-free classrooms, time limits, monitoring apps—but flying blind. For parents especially, the stakes feel high, but the evidence is thin.
“There are some difficult trade-offs that don’t often get highlighted,” Gentzkow says. “When parents impose very strict, almost draconian limits, it can increase conflict. Parents end up spending a lot of time fighting with their kids about the rules, which can actually make things worse.”
Which is what makes this research so urgent. Unlike many entrenched social problems, this one might be actionable with the right data. Clear evidence, Gentzkow argues, could directly guide parents, policymakers, and schools—helping them sort out which strategies actually protect kids and which might backfire.
Learn more about work made possible through Stanford Impact Labs 👉 https://stanford.io/4gxLsVW
