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-_-_-_-_-  1mo ago (natesilver.net)   2583 thread views

Nate Silver: The model exactly predicted the most likely election map

natesilver.net

Key excerpt (But it's worth reading the full thing):

But the real value-add of the model is not just in calculating who’s ahead in the polling average. Rather, it’s in understanding the uncertainties in the data: how accurate polls are in practice, and how these errors are correlated between the states. The final margins on Tuesday were actually quite close to the polling averages in the swing states, though less so in blue states, as I’ll discuss in a moment. But this was more or less a textbook illustration of the normal-sized polling error that we frequently wrote about [paid only; basically says that the polling errors could be correlated be correlated between states]. When polls miss low on Trump in one key state, they probably also will in most or all of the others.

In fact, because polling errors are highly correlated between states — and because Trump was ahead in 5 of the 7 swing states anyway — a Trump sweep of the swing states was actually our most common scenario, occurring in 20 percent of simulations. Following the same logic, the second most common outcome, happening 14 percent of the time, was a Harris swing state sweep.6

[Interactive table]

Relatedly, the final Electoral College tally will be 312 electoral votes for Trump and 226 for Harris. And Trump @ 312 was by far the most common outcome in our simulations, occurring 6 percent of the time. In fact, Trump 312/Harris 226 is the huge spike you see in our electoral vote distribution chart:

[Interactive graph]

The difference between 20 percent (the share of times Trump won all 7 swing states) and 6 percent (his getting exactly 312 electoral votes) is because sometimes, Trump winning all the swing states was part of a complete landslide where he penetrated further into blue territory. Conditional on winning all 7 swing states, for instance, Trump had a 22 percent chance of also winning New Mexico, a 21 percent chance at Minnesota, 19 percent in New Hampshire, 16 percent in Maine, 11 percent in Nebraska’s 2nd Congressional District, and 10 percent in Virginia. Trump won more than 312 electoral votes in 16 percent of our simulations.

But on Tuesday, there weren’t any upsets in the other states. So not only did Trump win with exactly 312 electoral votes, he also won with the exact map that occurred most often in our simulations, counting all 50 states, the District of Columbia and the congressional districts in Nebraska and Maine.

I don't know of an intuitive test for whether a forecast of a non-repeating event was well-reasoned (see, also, the lively debate over the performance of prediction markets), but this is Silver's initial defense of his 50-50 forecast. I'm unconvinced - if the modal outcome of the model was the actual result of the election, does that vindicate its internal correlations, indict its confidence in its output, both, neither... ? But I don't think it's irreconcilable that the model's modal outcome being real vindicates its internal correlations AND that its certainty was limited by the quality of the available data, so this hasn't lowered my opinion of Silver, either.

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Nate is incapable of questioning if polls contain any signal what-so-ever.

Polls are useless for 2 reasons: When the margins are narrow (2020, 2024), polls are too noisy to get anything of value

???

Ok from this post Nate links in his defense, emphasis mine: https://www.natesilver.net/p/the-polls-are-close-but-that-doesnt

But our forecast has been hovering right around 50/50 since mid-September. Donald Trump gained ground in mid-October, and Harris has regained just a little bit now, but it’s always remained comfortably within toss-up range. So if you believe the polls, we’re coming up on the end of the closest presidential race in 50 years. Harris leads by about 1 point in our national average — though our estimate of the national popular vote, which is mostly not based on national polls, shows a slightly wider margin than that1 — and the battleground states are even closer. Donald Trump has a 0.3-point lead in Pennsylvania, while Harris has small leads in Michigan (D +1.1) and Wisconsin (D +0.9).

However, that doesn’t mean the actual outcome will be all that close. If the polls are totally accurate we’re in for a nail-biter on Tuesday night. But a systematic polling error is always possible, perhaps especially if you think pollsters are herding — only publishing results that match the consensus. And because things are so close, even an average polling error would upend the state of the race.

Now it’s important to note that polling error runs in both directions, and it’s pretty much impossible to predict which way it will go ahead of time. Harris could beat her polls or we could be in for a third Trump miss. But both scenarios have one thing in common: they’d turn election night into a relative blowout.

So. This sounds to me like Nate explaining that the polls are too noisy to gain anything of value (about who wins at least). The 50/50 result sounds like it is a direct consequence of this and that it is precisely what Nate is claiming. Maybe the guy is incapable of coming to the right conclusions. Many of the crowd here did manage to predict the direction of the polling bias after all. But it sounds like that was all Nate was missing.

Now it’s important to note that polling error runs in both directions, and it’s pretty much impossible to predict which way it will go ahead of time.

I'm given to understand that this point in particular was straightforwardly false. Polling error leaned heavily toward undercounting Trump voters.

Right. That is in my conclusion yes.

So it is, my bad.

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