I wanted to share with you a few ideas, possible insights and caveats about campaign polls. These aren’t original to me in most cases, just some general points, observations, etc.
First, herding: Herding is the phenomenon in which even professional, good-faith polling operations start grouping together in the latter stages of a campaign because you don’t want to go too far out from the consensus numbers. Right now the national top lines have been between 2 and 4 points in Harris’ favor for a couple months. If you do a poll that gets you plus 10 in either direction, you’re going to think or are liable to think something’s wrong with your numbers. Somehow you’ve just got a spoiled set of data. Maybe you don’t release that poll or maybe you look again at the numbers and decide there are too few of some demographic subset and you re-weight that and it brings the topline back close to that 2-4 range.
It’s also the case that voter choice gets more settled in the final weeks of a campaign. So maybe the voters are actually herding themselves. There are lots of possibilities. But the general point here is that there are factors which can drive even ethical and professional pollsters in this herding direction.
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