Executive summary: A critical review of the evidence suggests that nonviolent protests likely work to influence electoral outcomes and public opinion in the U.S., based on natural experiments, although the generalizability of results is uncertain and the strength of evidence is somewhat overstated in the Social Change Lab’s report.
Key points:
Natural experiments show nonviolent protests increase vote share and public support: Five high-quality studies using quasi-experimental designs (mostly rainfall-based) found consistent positive effects of nonviolent protests on electoral outcomes and public opinion, though one (BLM) failed placebo tests and was excluded from the main meta-analysis.
Violent protests may backfire: Evidence from one quasi-experiment (Wasow 2020) and other studies suggests violent protests reduce support, supporting a bimodal hypothesis: nonviolent protests help; violent ones hurt.
Social Change Lab’s claims mostly hold up: Their “strong” and “medium” confidence findings are broadly supported, though their review overstates the strength of causal evidence and occasionally misrepresents individual studies.
Effect size is potentially substantial: Meta-analysis estimates a mean increase of ~12 vote share points per 100 protesters, but this estimate is sensitive to assumptions about publication bias and spatial autocorrelation.
Generality is limited: All analyzed protests were large, U.S.-based, and relatively mainstream; it’s unclear whether results apply to local or radical protests, or to non-U.S. contexts.
Methodological concerns moderate confidence: While natural experiments improve on observational studies, they face issues like spatial autocorrelation and potential publication bias; these limitations justify cautious interpretation despite encouraging results.
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Key point 1 is misleading. There were five high-quality studies, but only four found positive effects of nonviolent protests (the fifth only covered violent protests[^1]), and only three of those four were included in the meta-analysis. So we only have three strong studies showing a positive effect.
Key point 2 is fair.
Key point 3 is partially correct. Social Change Lab’s review did overstate the strength of some of the evidence, but I would not say it “misrepresented” individual studies. It did have a single incorrect numerical figure, which I suspect wasn’t a mistake, it was probably just pulled from an older revision of the study than the one I looked at.
Key point 4: I am not sure what “~12 vote share points per 100 protesters” is supposed to mean but it sounds incorrect. The mean effect was an increase of 12 turnout-adjusted voters per protester (that is, the electoral effect per protester was the same as if they’d moved 12 voters[^2] and there had been 100% turnout).
Key point 5 is fair.
Key point 6 is fair.
[^1] Technically Wasow (2020) covered both violent and nonviolent protests, but the part about nonviolent protests was purely observational (no natural experiment).
[^2] Where “moving” includes both persuading someone to turn out, and persuading someone to change who they vote for. (Those two things are not equivalent when you’re looking at absolute vote count, but they’re equivalent with respect to vote share.)
Executive summary: A critical review of the evidence suggests that nonviolent protests likely work to influence electoral outcomes and public opinion in the U.S., based on natural experiments, although the generalizability of results is uncertain and the strength of evidence is somewhat overstated in the Social Change Lab’s report.
Key points:
Natural experiments show nonviolent protests increase vote share and public support: Five high-quality studies using quasi-experimental designs (mostly rainfall-based) found consistent positive effects of nonviolent protests on electoral outcomes and public opinion, though one (BLM) failed placebo tests and was excluded from the main meta-analysis.
Violent protests may backfire: Evidence from one quasi-experiment (Wasow 2020) and other studies suggests violent protests reduce support, supporting a bimodal hypothesis: nonviolent protests help; violent ones hurt.
Social Change Lab’s claims mostly hold up: Their “strong” and “medium” confidence findings are broadly supported, though their review overstates the strength of causal evidence and occasionally misrepresents individual studies.
Effect size is potentially substantial: Meta-analysis estimates a mean increase of ~12 vote share points per 100 protesters, but this estimate is sensitive to assumptions about publication bias and spatial autocorrelation.
Generality is limited: All analyzed protests were large, U.S.-based, and relatively mainstream; it’s unclear whether results apply to local or radical protests, or to non-U.S. contexts.
Methodological concerns moderate confidence: While natural experiments improve on observational studies, they face issues like spatial autocorrelation and potential publication bias; these limitations justify cautious interpretation despite encouraging results.
This comment was auto-generated by the EA Forum Team. Feel free to point out issues with this summary by replying to the comment, and contact us if you have feedback.
My review of this summary:
The executive summary is fair.
Key point 1 is misleading. There were five high-quality studies, but only four found positive effects of nonviolent protests (the fifth only covered violent protests[^1]), and only three of those four were included in the meta-analysis. So we only have three strong studies showing a positive effect.
Key point 2 is fair.
Key point 3 is partially correct. Social Change Lab’s review did overstate the strength of some of the evidence, but I would not say it “misrepresented” individual studies. It did have a single incorrect numerical figure, which I suspect wasn’t a mistake, it was probably just pulled from an older revision of the study than the one I looked at.
Key point 4: I am not sure what “~12 vote share points per 100 protesters” is supposed to mean but it sounds incorrect. The mean effect was an increase of 12 turnout-adjusted voters per protester (that is, the electoral effect per protester was the same as if they’d moved 12 voters[^2] and there had been 100% turnout).
Key point 5 is fair.
Key point 6 is fair.
[^1] Technically Wasow (2020) covered both violent and nonviolent protests, but the part about nonviolent protests was purely observational (no natural experiment).
[^2] Where “moving” includes both persuading someone to turn out, and persuading someone to change who they vote for. (Those two things are not equivalent when you’re looking at absolute vote count, but they’re equivalent with respect to vote share.)