(1) On the evidence base for mass media interventions: Our choice to prioritize mass media (and so attempt more detailed modelling) was based on it (a) looking good in cost-effectiveness at a a shallower research stage with a less; (b) being recommended by the WHO as the most cost-effective intervention for promoting physical activity; and (c) generally, mass media interventions being 2nd only to policy in cheap scalability.
We relied on the study you cited (Abioye, Hajifathalian & Danaei), and took into consideration all three meta-analyses (impact on sedentary behaviour, sufficient walking, and sufficient physical activity), while discounting based on the degree to which measured outcome is dissimilar to GBD/​WHO definitions of sufficient physical activity (>= 600 METs minutes per week). We did not exclude the sedentary meta-analysis results based on the fact that its reliant on a low quality outlier, but did perform our own analysis, to discount it (and the other meta-analyses) on the basis of underlying study quality (especially with respect to endogeneity) and publication bias.
We also considered whether the studies being from high-income countries biases the result (n.b. on the one hand, ageing high income countries are older and more sedentary, which implies a larger group of potential beneficiaries and greater population-level effect size; on the other hand, as Rosie Bettle of FP notes in her report on mass media interventions, its potentially the case that basic healthcare knowledge is more lacking in poorer countries, so you can—as with vaccine uptake—increase uptake there in a way).
Overall, we do think there’s is an effect, but it’s highly uncertain, and there’s a real chance it’s zero. For more details, see the ultra-long (and fairly tedious) discussion in this cell (Tractability:B12) of the CEA.
(2) Built environment changes: We did take a look at this option (seeAnnex A in our CEAfor a qualitative discussion of the available intervention options, and the relevant evidence base/​expert feedback). We ultimately prioritized mass media (for reasons discussed above), but I do think such environment changes will be substantially more impactful but also much, much harder.
For one, if we’re talking about not just high-income countries but LMICs, the situation is very different. Zoning is justmuch less a factorthan in the rich world (they may not have much on the books, and what’s on the books may not be enforced), so the problem they face isn’t the one that the US/​UK etc face and which YIMBYs are trying to solve. Their major cities are also extremely dense, and people havelow vehicle ownership rates(but worse congestion and air pollution). Making these cities more walkable isn’t just a matter of allowing dense housing, but spending a lot of money to improve public transport, solving air pollution etc, and that’s a fundamentally much harder ask for poor countries.
Thanks for the thoughtful comment!
(1) On the evidence base for mass media interventions: Our choice to prioritize mass media (and so attempt more detailed modelling) was based on it (a) looking good in cost-effectiveness at a a shallower research stage with a less; (b) being recommended by the WHO as the most cost-effective intervention for promoting physical activity; and (c) generally, mass media interventions being 2nd only to policy in cheap scalability.
We relied on the study you cited (Abioye, Hajifathalian & Danaei), and took into consideration all three meta-analyses (impact on sedentary behaviour, sufficient walking, and sufficient physical activity), while discounting based on the degree to which measured outcome is dissimilar to GBD/​WHO definitions of sufficient physical activity (>= 600 METs minutes per week). We did not exclude the sedentary meta-analysis results based on the fact that its reliant on a low quality outlier, but did perform our own analysis, to discount it (and the other meta-analyses) on the basis of underlying study quality (especially with respect to endogeneity) and publication bias.
We also considered whether the studies being from high-income countries biases the result (n.b. on the one hand, ageing high income countries are older and more sedentary, which implies a larger group of potential beneficiaries and greater population-level effect size; on the other hand, as Rosie Bettle of FP notes in her report on mass media interventions, its potentially the case that basic healthcare knowledge is more lacking in poorer countries, so you can—as with vaccine uptake—increase uptake there in a way).
Overall, we do think there’s is an effect, but it’s highly uncertain, and there’s a real chance it’s zero. For more details, see the ultra-long (and fairly tedious) discussion in this cell (Tractability:B12) of the CEA.
(2) Built environment changes: We did take a look at this option (seeAnnex A in our CEA for a qualitative discussion of the available intervention options, and the relevant evidence base/​expert feedback). We ultimately prioritized mass media (for reasons discussed above), but I do think such environment changes will be substantially more impactful but also much, much harder.
For one, if we’re talking about not just high-income countries but LMICs, the situation is very different. Zoning is just much less a factor than in the rich world (they may not have much on the books, and what’s on the books may not be enforced), so the problem they face isn’t the one that the US/​UK etc face and which YIMBYs are trying to solve. Their major cities are also extremely dense, and people have low vehicle ownership rates (but worse congestion and air pollution). Making these cities more walkable isn’t just a matter of allowing dense housing, but spending a lot of money to improve public transport, solving air pollution etc, and that’s a fundamentally much harder ask for poor countries.