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Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

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Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#191

Post by rsynnott »

untog wrote: post #80
School-Cotton wrote: post #41

Earlier quoted context omitted.

Nate Silver said Trump had a 1 in 3 chance, which basically means one shouldn’t be surprised no matter the result. I’m not sure where this “all the polls were so far off in 2016!!” narrative comes from, but it’s wrong.

Nate was the outlier in that respect. But it’s true that the polls aren’t weren’t all that inaccurate in 2016: a bunch of important swing states were within the margin of error and Trump won some important states by very small margins. The mistake in 2016, IMO was a) the extrapolation that came from those polls and b) people paying way too much attention to national polls, which have very little connection to elector…

> But people read “90% chance” as “definite win”. I don’t actually know what anyone should or could do about that.

538 are aware of the problem, and combating it with a cartoon fox (and better visualisations).

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#192

Post by rsynnott »

ceilingcorner wrote: post #136
thomasmeeks wrote: post #132

Earlier quoted context omitted.

If you'd like to not be downvoted into oblivion you'd do well to provide an alternate theory. What's your prediction for the upcoming election? Why? What's your methodology? Or is your point that forecasting is futile? I can't tell. There's too much emotion directed at 538/etc. for me to suss out what your point is besides disliking 538/the media/etc, which just isn't particularly helpful for the discussion.

I wish it were that simple. HN just seems to have gone the way of reddit, where downvoting is disagreement. And of course, 3 minutes after I post this comment, it's downvoted. I don't have a methodology, because I'm not a pollster with dozens of people at my disposal. I am just bemused and annoyed that things like 538 continue to be taken seriously when they continue to ignore sociological, historical, and cultural f…

> Biden is a much weaker candidate than Hillary and he continues to make blunders

That’s your view; however, he is polling much better than Clinton, which would indicate that voters don’t necessarily agree with you (or else just that peoples’ opinions of Trump are lower than last time round, or a combination. But really it hardly matters).

> (i.e. I guarantee that his comments on fracking in the last debate just lost him Pennsylvania.)

Looks like 20-50,000 people employed in fracking plus industries supported by it in Pennsylvania. And presumably most of those would be voting for Trump anyway; it’s not like Biden’s views on fracking were a total black box til now. So it only really matters if it’s very close anyway.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#193

Post by SamReidHughes »

croissants wrote: post #112
justinzollars wrote: post #96

Earlier quoted context omitted.

I know people that have moved, but forgot to register. Its a fact of life that voter registration will take the back seat when managing more complicated things in life - like a move

That seems plausible. Still, I think the "exodus from cities" theory doesn't apply much to American cities outside of New York and San Francisco. Places like Philadelphia may have even seen a small uptick from NY emigration. But this is just a guess, it would be nice to see any statistics (I haven't found any).

Here in San Diego, for instance, we've generally had net inbound migration. It's pretty much the opposite of Philly, though, in terms of both coronavirus and violence. But it is an "alternate choice" backwater city, compared to SF or LA, kind of like the way Philly is to New York.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#194

Post by rsynnott »

newfeatureok wrote: post #27

The thing about this election is that what if Trump himself is some sort of wildcard that can't really be properly forecasted in the polls? Why is there so much fascination with polls to begin with? I understand that there are betting markets, but it seems sort of silly. If you had a 100% accurate poll, for instance, then what would be the purpose of the actual election?

> The thing about this election is that what if Trump himself is some sort of wildcard that can't really be properly forecasted in the polls?

The only way that would work is if he made people more likely to lie about their voting intentions. Now, there may be something about Trump that makes polling methodologies less accurate (notably, many pollsters have started to take into account education, which turned out to be unexpectedly important last time round) but that points just to bad methodology, not inherent unpredictability.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#195

Post by sellyme »

ceilingcorner wrote: post #136
thomasmeeks wrote: post #132

Earlier quoted context omitted.

If you'd like to not be downvoted into oblivion you'd do well to provide an alternate theory. What's your prediction for the upcoming election? Why? What's your methodology? Or is your point that forecasting is futile? I can't tell. There's too much emotion directed at 538/etc. for me to suss out what your point is besides disliking 538/the media/etc, which just isn't particularly helpful for the discussion.

I wish it were that simple. HN just seems to have gone the way of reddit, where downvoting is disagreement. And of course, 3 minutes after I post this comment, it's downvoted. I don't have a methodology, because I'm not a pollster with dozens of people at my disposal. I am just bemused and annoyed that things like 538 continue to be taken seriously when they continue to ignore sociological, historical, and cultural f…

> HN just seems to have gone the way of reddit, where downvoting is disagreement.

Alternatively it might be because you're objecting to the results of a well-documented statistical process, and then when being questioned saying things like "I don't have a methodology".

You'll notice that the comment you replied to (saying it was similar to your point) is not downvoted into oblivion.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#196

Post by Ibethewalrus »

patrickthebold wrote: post #78
Ibethewalrus wrote: post #64

Earlier quoted context omitted.

nope, you're wrong. 538 gave Hillary a 71.4% chance of winning https://projects.fivethirtyeight.com/2016-election-forecast/

The GP is saying 538 did better compared to other news outlets. You need to also provide a source for another news outlet giving Hillary less than 71.4% if you want to show that the GP is wrong.

thanks. gave a reread to the comment I replied to and makes sense

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#197

Post by TMWNN »

ceilingcorner wrote: post #136
thomasmeeks wrote: post #132

Earlier quoted context omitted.

If you'd like to not be downvoted into oblivion you'd do well to provide an alternate theory. What's your prediction for the upcoming election? Why? What's your methodology? Or is your point that forecasting is futile? I can't tell. There's too much emotion directed at 538/etc. for me to suss out what your point is besides disliking 538/the media/etc, which just isn't particularly helpful for the discussion.

I wish it were that simple. HN just seems to have gone the way of reddit, where downvoting is disagreement. And of course, 3 minutes after I post this comment, it's downvoted. I don't have a methodology, because I'm not a pollster with dozens of people at my disposal. I am just bemused and annoyed that things like 538 continue to be taken seriously when they continue to ignore sociological, historical, and cultural f…

I agree that there are factors that so much of current reporting is missing. The black (and Latino) swing toward Trump, for example, is apparent in every single poll I've seen. As mentioned elsewhere in this discussion Nate Silver's discussed it, but little else other than the odd article like https://www.nytimes.com/2020/10/14/us/politics/trump-macho-a... (which basically attributes male Latino support for Trump to the same machismo that ruined their ancestors' countries). Same with the increase in black Trump support from 2016%'s 8%, even though it's pretty clear from history that no Democrat can win the White House without at least 85% of the black vote.

>At this point my estimation is Trump-Biden 55-45, for the simple reason that people tend to vote for economic issues and Trump has a better "perception" on this issue. "It's the economy, stupid." as James Carville put it.

Indeed, Gallup reports that 56% of Americans believe that they are better off than four years ago (https://news.gallup.com/opinion/gallup/321650/gallup-electio...).

My model is simpler. If Trump wins every other state he won in 2016, he only has to win one of MI, PA, WI, MN, or NH/NV. The first three he won in 2016 (and, as you say, Biden's views on fracking may very well cost him the state); MN Trump lost by 1.5%, so the state is only sightly behind the rest of the Midwest bar IL, and half of Minneapolis being torched this summer probably pushed the state over.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#198

Post by DavidSJ »

RivieraKid wrote: post #179
DavidSJ wrote: post #124

Earlier quoted context omitted.

Other way around: uncorrelated errors tend to cancel each other, correlated errors tend to reinforce each other.

Well Gelman claims the opposite.

No, what Gelman says is that he suspects that to compensate for the fat tails in 538's state distributions, they had to reduce the between-state correlations, to get a desired overall level of uncertainty.

This implies that correlations increase, rather than decrease, the overall level of uncertainty.

This is also easy to see from a basic probability perspective, using the concept of variance. For example, if you have two coin flips, with outcomes {-1, +1} chosen uniformly at random, then the sum has variance 2 if the flips are independent, but variance 4 if the flips are perfectly dependent.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#199

Post by pessimizer »

sequoia wrote: post #175

As a US voter I am very frustrated With and tired of this obsession with election forecasting. Is it going to influence whether or not you go out and vote? If not, what is the point of it? What value does something like fivethirtyeight add to our democracy, if any? Is this motivation the same as that of diving deep into baseball stats or Star Wars starship engineering, just like “nerding out” for its own sake? Contra…

There's nothing scientific about any of this trash. It's a weird conflation of the degree of the incompetence of pollsters and the degree to which opinions can be changed within a span of time. And it's completely unfalsifiable. When Trump wins, the true believers will say "We gave him a 9.684% chance of winning! It's only your ignorance that makes you think we were wrong" and they go back to poring over their race tables.

It's an orgy of false precision.

edit: the entire debate is based on the weird assumption that if a prediction about a particular state is wrong, then pollsters must have systematically gotten middle-class Hispanic women over 40 wrong, therefore the odds of other states will change. It's all based in the reification of particular categories that are axiomatically significant for their profession.

Re: Reverse-engineering the problematic tail behavior of Fivethirtyeight forecast

#200

Post by wisty »

screye wrote: post #145

I disagree with the author on the idea that tail is too fat for isolated anomalies. There are most certainly events that can happen, which may lead to a red California or a blue Alabama. Presidential assassination, war, video proof of something incredibly heinous (pedophilia?), etc. can absolutely lead to these outcomes. You don't even have to go that far back. Nixon and Reagan flipped states like no-one's business.…

OK, so is this your point?

Something could flip California and Alabama (example, Trump starts defending Roe v. Wade and in response Biden somehow manages to sound like he's opposing it). This would probably be some latent hidden variable, like whether the candidates are seen as socially conservative, which would effect all states (though California and Alabama would be the most impacted).

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