Adolescents in better mental health
The best causal evidence on this question comes from Facebook's arrival at American colleges one at a time between 2004 and 2006. Where it arrived, symptoms of depression and anxiety rose, and the mechanism the authors identify is unfavourable comparison with other people. The bill removes the part of the product that does the comparing.
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Value
The stream is the mental health of people between about eleven and seventeen: how much they sleep, whether they are anxious in a way that interferes with school, how they feel about their own life against everyone else's. This site places it in the class it uses for life and health, one step below the top because adolescent low mood is generally recoverable and because what is measured is a symptom index rather than a diagnosis. The weight does not rise because the people concerned are young; what youth changes is how long the consequences run, and that belongs to the Impact. The academic consequences are counted separately in the next argument. The value sits one step below the maximum: the stream is health, and health that can be regained.
Impact
About 17 million Americans are aged 13 to 16, and several million more are under 13 and hold accounts anyway. The size of what a feed does to them comes from the one clean measurement available: Facebook arrived at American colleges at different dates, and where it arrived, symptoms of poor mental health rose by about a tenth of a standard deviation — roughly a fifth of the effect the same authors compute for losing one's job [4]. Removing algorithmic recommendation is not the same as removing the platform, so 30 percent of that effect is used here, in a range from 10 to 60 percent: about 0.025 standard deviations across 17 million teenagers, plus a larger effect on the roughly 4 million under-13s who would lose accounts entirely. A standard deviation on such an index is worth roughly 0.06 quality-adjusted years, in a range from 0.03 to 0.12. The two together give about 40,000 quality-adjusted years a year. The Impact is the largest in this debate, and it is large because of how many adolescents there are rather than how much happens to each of them.
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| Americans aged 13 to 16 | 17 million people | ||
| × | Improvement in symptoms of poor mental health Setting, range 10 to 60 percent of the measured effect: Facebook's arrival at a college raised symptoms by about a tenth of a standard deviation, and this measure removes one feature rather than the platform [4] | 0.025 standard deviations | 425,000 standard-deviation-people |
| + | Under-13s who lose accounts entirely a larger effect, because the account goes rather than the feed | 4 million × 0.06 standard deviations | 665,000 standard-deviation-people |
| × | Quality-adjusted years per standard deviation Setting, range 0.03 to 0.12 | 0.06 | 39,900 quality-adjusted years |
| × | Value of the years the value of a healthy life year used across this site | 40,000 euro each | 1,596 million euro |
| ÷ | Normalised Impact scale of this evaluation | 200 million euro a point | 8 |
Plausibility
This is the most contested empirical question in the area and the evidence divides by design rather than by conclusion. The counterfactual in the study carrying this figure is colleges that had not yet received Facebook, compared against those that had, on the same survey instrument before and after [4]. The confounder that would otherwise dominate — that early colleges differ from late ones — is what the staggered rollout absorbs, and reverse causation cannot arise, since a student's mood did not determine when Facebook expanded. Against that, meta-analyses of the wider literature repeatedly find effects near zero, and they are right to: most of that literature is cross-sectional and measures who uses social media rather than what it does. Two things limit the transfer here. The study is about college students in 2004 and this measure concerns adolescents in 2026, whose product is a video recommendation engine rather than a list of friends' profiles. And the study measures a platform arriving, while this measure removes one feature of it — which is why only 30 percent of the effect is carried across. The Plausibility is below the middle: the design behind the number is sound, and almost everything about the transfer to today's product is assumed.
Counterfactual: American colleges that had not yet received Facebook, on the same survey instrument. Design: quasi-experimental — generalised difference-in-differences on a staggered rollout (Braghieri, Levy and Makarin, American Economic Review 2022 [4]). Confounder: early-adopting colleges differing from late ones, absorbed by the staggered timing. Direction: no reverse causation, student mood did not determine Facebook's expansion order. Ceiling: quasi-experimental 8.0 binds below the studie ceiling of 9.0; a context transfer of 3.5 applies for two separate gaps — college students in 2004 against adolescents in 2026, and a platform arriving against one feature being switched off. The size doubt sits in the 10 to 60 percent band, not in P.
The chain is named and its one measurement is good: a staggered rollout, a tested comparison, no reverse causation. What is missing is a measurement on today's product. The meta-analyses that find effects near zero are not a counter-finding on the same outcome, because they are cross-sectional and measure who uses social media rather than what it does — a different question under a design that cannot answer this one. Read back: about half the time, switching off algorithmic feeds improves adolescent mental health by roughly the amount assumed here.
Open: Australia removed 4.7 million under-16 accounts on a single date in December 2025. A comparison of adolescent mental health measures against a similar country over three years would replace the whole transfer with a direct measurement and could carry P to 7.