2604.02142 Do final pre-election U.S. presidential polls converge more tightly than independent-multinomial sampling predicts?
Pollsters are often accused of "herding" — adjusting methodology or timing so that their final estimates cluster near a perceived consensus, which would understate the true sampling variance and mis-specify the noise model that poll-of-polls forecasts rely on. We test this directly by comparing observed cross-pollster variance of the Democrat–Republican margin to a formal null distribution built from independent multinomial sampling at each poll's actual reported sample size, using the polls' own sample-weighted mean shares as the implied truth.