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Comment by xoxoy | Hacker News Reader

If anyone followed the betting odds on election night at one point the prediction markets went from heavy Biden favorite to heavy Trump favorite as he won Florida and it looked like he was ahead in a lot of the swing states, but for weeks pundits had been saying it might look like Trump would be ahead in these states early on due to propensity for conservatives to vote in person on election day and for democrats to vote by mail, which turned out to be true.

if these markets were actually good predictors I don’t think the wild swings we saw overnight would have happened.

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Those are two different things. The red and blue shifts from in-person and mail votes were very reasonably predicted before the election. But the reason the probability of a Trump win rose so much was that Florida turned out red by quite a bit compared to the polls and if that polling miss was systematic Trump would have won. It later became clear that the Florida miss was specific to that state, probably because of specific demographics and the probabilities swung in Biden's favor again.

>the prediction markets went from heavy Biden favorite to heavy Trump favorite as he won Florida and it looked like he was ahead in a lot of the swing states

I wonder how much of the "polls were wrong" narrative is due two specific issues: Miami-Dade county being surprisingly pro-Trump and the pandemic leading to more mail ballots and slower counting. That helped establish a narrative early on election night which caused that action on the prediction markets. However if you told someone three weeks ago that Biden would win 306 electoral votes and win the popular vote by some 7 million votes, which seems to be where we will end up, would they think there was any sizable systemic failure? I would guess they wouldn't.

Some of "the polls were wrong" talk started before all the votes were counted, definitely. In certain states (WI most notably) the polls were definitely far off. I don't know if there were more states where polling was inaccurate than normal, though.

Were they really "far off" outside of Wisconsin and Miami-Dade county? Those were the only two results that seemed truly surprising. Results like North Carolina going from Biden ahead by 1% to Trump ahead by 1% or Michigan going from Biden up 7% to up 3% are perfectly normal polling errors. In a normal election, I think there would have been a good chance that the polling miss in Wisconsin would have been an afterthought after Biden was declared the winner late Tuesday or early Wednesday.

Iowa, Texas, and Ohio weren't close and polls had them there. Those were all about 5% off. I don't know how many states end up that far off in typical elections. Maybe Ohio ends up closer, once counting is done there.

(I wasn't surprised by those results and the campaigns didn't act like they were close, so.)

Double checking my memory, I see Maine 2 was way off! Not gonna get too worried about that. That one's hard. https://fivethirtyeight.com/features/the-polls-werent-great-...

Fair point about those three states. They were often ignored because if they went for Biden it meant there was a huge landslide in his favor. If you click through one of those links in that linked article you get to this[1] article from 2018 that lists the average polling error at 5.9%. Maybe it is just people have unrealistic expectations for these things any miss beyond a point or two is going to be dubbed as "THE POLLS ARE WRONG!".

[1] - https://fivethirtyeight.com/features/the-polls-are-all-right...

For the Presidential election, I don't think any other states were too far outside the margin of error, but there were a lot of high-profile downballot races with similarly absurd differences. Susan Collins did something like 12 percentage points better than her polling.

This was the first go for ranked choice voting in that Maine Senate race. I don't think anyone should draw any drastic conclusions from a polling miss there.

Oh, I actually didn't realize that, I thought they'd had it for a while. I agree that complicates things.

Missouri, for instance, was off by 8 points between 538 model and results. That seems well outside a normal polling error.

Could you clarify this? According to the results I'm seeing, in Missouri Trump got 56.9% and Biden got 41.3%. I can't imagine anyone was predicting 8% less for Trump and more for Biden. That would have Biden winning Missouri, which would have been ridiculous. An 8% different prediction in the other direction also seems implausible. Perhaps you could link to the 538 prediction?

That's a 16 point win for Trump. The polls were predicting an 8 point win e.g. 54/46

Thanks, that makes sense. I vote in one the hillbilliest locations in the state. When I arrived at 6 AM and saw the several-hundred-feet-long line of people, I knew the Trump vote was going to be higher than I had expected going in.

A third issue: the House and Senate polling was way off, much worse than the presidential contest.

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