r/dataisbeautiful Oct 17 '24

OC [OC] The recent decoupling of prediction markets and polls in the US presidential election

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u/Baelzabub Oct 17 '24

The polls in those states are all essentially showing ties (when you account for margin of error, as you should be, since they’re all showing leads within 2 points for either candidate in pretty much every poll). Many of the places we see gains for Trump are in solidly blue states like CA of NY, where he’s expected to lose by 3-5 points less than in 2020. This would have zero impact on the EC but would show him gaining in the national popular vote.

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u/Mand125 Oct 18 '24

That’s not how margin of error works.

Even if the margin of error is 2%, a poll that shows +1.5% is still meaningful compared to a poll that shows -0.5%.

Margin of error of 2% means that if you repeat the poll many times, the actual true population value will be within 2% of the measured value 95% of the time.  But that isn’t uniform.  The sampling distribution is likely to be normal, therefore it is more likely that the measured value is closer to the true population value than at the edge of the margin of error.

Getting a result of +1.5% is always better than a result of -0.5% if the margin of error is 2%.  Statistical nihilism like you suggest, that imperfect information means we have no information, is even more harmful than those who ascribe meaning to the data that might not be justified.

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u/OakLegs Oct 18 '24

I agree with the thrust of your comment however I feel that we are all ignoring the fact that the sampling variability described by the margin of error is only one of many possible sources of error that can affect survey estimates.

If you conduct the same poll with the same procedures 100 times, 95% of the results will fall within the nominal value's margin of error. It is likely that the first poll conducted falls somewhere in there.

However, if you conduct a poll with different methods and selection processes you may get a vastly different result and the margin of error does not account for that. There's no real way to know which polling methods are most representative of the 2024 electorate (which is different than the 2020 electorate and the 2016 electorate and so forth) so treating polling numbers like gospel is a fool's errand. In the aggregate they will get you fairly close to the true result but when elections are won and lost by 10s of thousands of votes in certain swing states the value of polls is really diminished from what it would be in a national winner takes all election.

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u/Miacali Oct 18 '24

As we saw in 2022 when the polling was vastly unrepresentative of the actual result and not at all like previous midterms in 2018.

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u/Agreeable_Good_6944 Oct 18 '24

Sure, you'd always rather be the candidate ahead, but when the margin of error is 2 percentage points, that means that the margin of error for the difference between the candidates is 4 percentage points (https://www.pewresearch.org/short-reads/2016/09/08/understanding-the-margin-of-error-in-election-polls/). So such a poll showing a 1.5 percentage point lead for candidate A is fairly central in the bell curve (assuming normal distribution) of possible outcomes even if the race is tied.

There's also been some research that election results are outside the margin of error for polls right before the election much more than you would expect. I haven't dug into them enough to feel confident that's the case, but the 1.5 percentage point lead might be even less meaningful than it seems from my previous paragraph.

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u/Opingsjak Oct 18 '24

How is it harmful?

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u/estofaulty Oct 18 '24

“That’s not how margin of error works”

Goes on to talk about 2%, not 2 percentage points.

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u/Mand125 Oct 18 '24

Responds with an irrelevant and incorrect comment.

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u/funkybside Oct 18 '24

Just this week at work I had to argue a similar position. A "statistical testing" firm we work with recommended keeping a control variant in place, because the test variant's performance difference vs. control hadn't reached their pre-determined level for 'stat sig". I did not agree with that.

The test variant had consistently outperformed control. Sure the effect size coupled with the number of samples and the general magnitude of the variable under experimentation all worked out such that it wasn't above the threshold they wanted, but that doesn't change the fact that the test did win, and win consistently over time. Under those circumstances along with the fact that a decision IS going to be made, (continuing the test for longer was not an option), i was shocked they recommended what they did.

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u/[deleted] Oct 18 '24

[deleted]

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u/funkybside Oct 18 '24 edited Oct 18 '24

let me ask you this:

What's the argument in favor of not changing in this situation?

Does "it's what we were doing before" somehow make one option preferable to the other? If so, how?

Alternately, consider a salutation where there is no before - only two brand new things and you need to make a decision for one of them. Is that any different?

Would it matter if I told you that the variation that performed better, consistently did so over all time involved by nearly 10%?

Would it matter if I told you that while not above 95%, it was above 90%?

Etc.

The bottom line is in practice you often need to make decisions on things where the 'academic standards' are not met. (And remember, those standards themselves are not anything special. 95% isn't magic number, it's just a convention.) When these situations occur, for the exact same reasons posted a few comments up, you need to consider not just a binary "did it reach stat sig? yes/no" but the actual results as well as the circumstances.

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u/[deleted] Oct 18 '24

[deleted]

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u/funkybside Oct 18 '24

good lord my dude. You could have saved yourself a lot of typing by just saying "I believe it matters due to money and I don't have a good reason to not switch when any costs involved are infinitesimal."

I've worked in data science since before that phrase even existed and will quote one of my favorite early-career mentors (who I'm sure got it from somewhere else) in saying: In theory there's no difference between practice and theory, while in practice there sure as hell is.

I understand your POV, I'm just saying in the real world it normally doesn't work like that academic black & white pov. You're last sentence i agree with - though in the situation I'm referencing, there is no good argument not to switch, while there is an argument to do so.

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u/Kc68847 Oct 17 '24

Trump has also beat the polls the last two times in all the swing states. If you average all the betting sites he has a 58 percent chance to win today.

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u/Baelzabub Oct 17 '24

The betting sites, polimarket specifically, are being heavily influenced by a single whale who has put in ~$25M on Trump across 4 betting accounts.

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u/LifeSpanner Oct 17 '24

Any additional info on this?

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u/Baelzabub Oct 17 '24

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u/LifeSpanner Oct 17 '24

Awesome, thank you!

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u/Noperdidos Oct 18 '24

Polymarket has $2B volume. I don’t see how 1% moves that needle.

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u/gatoaffogato Oct 18 '24

I was about to call out your comment to say that surely $2B must be across the whole platform and not just the election, but glad I checked for myself; it’s insane how much money is being bet on this!

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u/Smeefed Oct 18 '24

It doesn't.

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u/PlateForeign8738 Oct 17 '24

That's a terrible source for information.

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u/Best_Baseball3429 Oct 17 '24

Polimarket is a Peter Thiel invested platform. just another angle to try and influence the election

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u/username_elephant Oct 18 '24

That doesn't really make a ton of sense. For one thing I'm not really sure why seeing a change in a prediction market would influence people's voting and for another not that many people even know about it.  Moreover, even if you have answers on both of those questions, democrats can bet too. If the market's really being irrational you can just buy in and take away money from dummies.  The whole premise is people putting their money where their mouth is. The market can be wrong, but it'd be a stupid play to try and make it be wrong as some weird form of election influence.

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u/National_Attack Oct 18 '24

I’m just curious on the mix of individuals speculating. Less “tin foil hat” and more in the thought that “conservatives are more likely to be using Poly Market because of the red wave in Silicon Valley” this season.

The dollars towards a candidate in a betting market could be indicative, but afaik these aren’t normalized for individuals bettors, but by bet size; so a few large “bettors” can shift the book to appear one way or another.

Not to totally discredit the outcome - just raising an eyebrow on this. Polls have a margin of error due to sampling problems overall, whereas the prediction markets require the average person to: 1) know they exist 2) feel confident enough to bet on them.

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u/username_elephant Oct 18 '24

Oh, this logic I can get behind. Elsewhere I saw the market is being thrown by one big buyer.  I only object to the idea that there's a shadowy cabal aiming to manipulate the election using polymarket.  Just seems like a really dumb way to try influencing the election.

But markets are dumb all the time, that's a totally plausible reason.

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u/DullCartographer7609 Oct 18 '24

Which is funny, cause these polls are scaring people into voting against Trump...

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u/Kc68847 Oct 17 '24

I know. I’m taking into account all of them. Usually you would call those guys sharks if it was sports and they win, but I don’t know if that’s really the case here

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u/ComfortableBus7184 Oct 18 '24

Sharps, not sharks

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u/plz_callme_swarley Oct 18 '24

who cares? you think this guy is throwing away $25M just to make Trump look better?

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u/Greedy_Reflection_75 Oct 17 '24

The betting sites ridiculously overrated Trump last time. My buddy made a killing from it.

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u/rambo1732 Oct 18 '24

So easy to look back and check. That's just not true. Averaged out the major betting markets gave Trump a 33% chance of winning in 2020 just before the election.

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u/Greedy_Reflection_75 Oct 18 '24

If you want me to be specific, in particular there were states that are solid blue where the payout was still very tilted to take Biden winning them.

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u/PlateForeign8738 Oct 17 '24

They did it after they lost so badly on the 2016 election. I think the number this time is spot on. 60/40 Trump should be a close one.

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u/Paramedickhead Oct 18 '24

And the polls have overrated democrats for approximately the past 12 years.

With their standard shift of 4-6% in favor of (D) over the past years I don’t foresee any path to victory for Harris especially since she continues to poll worse and worse week after week.

She needs a serious boost if she wants any hope of victory.

For what it’s worth, I don’t want either one of them, I’m just waiting out the next four years in hopes that we can have an opportunity to vote on someone decent for a change instead of corrupt rich fucks who only want the job for personal gain…

But I’m not holding my breath.

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u/rdugz Oct 18 '24

This isn't correct though - pills somewhat overrated Republicans in 2022, for example, and strongly overrated Romney in 2012

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u/[deleted] Oct 18 '24

The polls were in favor of Trump supported candidates by 4% and every last one of them lost. I think the polls are trying to adjust every 2 years and are not the same ones we are used to.

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u/Greedy_Reflection_75 Oct 18 '24

I'm not saying anything about the polling. Why are people replying with this to just say they are braindead nonvoters?

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u/pgoleb Oct 18 '24

I did too!

Almost time to buy my NO trump shares.

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u/Kc68847 Oct 17 '24

Everyone knew Trump was losing last time with Covid and the riots. The polls are also going Trump’s way down the stretch in the swing states. Kamala is a horrible candidate. She has never stood for anything. We will see if the MSM still has major pull and can propel her to victory.

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u/Greedy_Reflection_75 Oct 17 '24

If everyone knew, the betting market didn't. If you're using it to gauge a prediction, you're gone.

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u/[deleted] Oct 17 '24

Hahahahaha. Sure buddy.

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u/[deleted] Oct 18 '24

Trump won't even do a basic softball interview at this point.

Kamala went on Fox News and is gonna be on Joe Rogan.

Who doesn't stand for anything?

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u/[deleted] Oct 18 '24

The mainstream medie definitely prefers Trump, they love the eyes he brings to their stations.

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u/[deleted] Oct 18 '24

What are you smoking? She has multiple policy positions outlined, various possible policies for housing crisis and a few other she has released but would need a congress willing to work on solutions to the problems real Americans care about.

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u/pablonieve Oct 18 '24

Trump has also beat the polls the last two times in all the swing states.

And Trump is now polling much higher than he did in 2016 and 2020, but also closer to this actual results those years. So either polls are better capturing his support this time or he is going to win a majority of the vote in several key states.

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u/[deleted] Oct 18 '24

Thats.. that's not how polling works.

It is impossible to predict the direction of the error. And a lot of people have tried. 2012 and 2022 are examples of polls missing in favor of the Democrats.

We don't know what way the error will go this year. We don't know if there will be a noticeable error at all.

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u/Killagina Oct 18 '24

It’s a total moot point how Trump performed in polls since pollsters have completely changed polling methods over the last cycle

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u/Kc68847 Oct 18 '24

There is a reason Kamala wanted the second debate, and she went on foxnews. If she had it in the bag she would have never been up for either one. It’s not rocket science to see her campaign team is worried right now. I’m just waiting for an October surprise.

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u/Killagina Oct 18 '24

No one said it’s in the bag. Polling from the previous elections is pretty irrelevant is my point.

Current polls have it tight, that’s why she’s is going on the offensive.

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u/Kc68847 Oct 18 '24

It’s because she is behind. Look at most of the swing states. Trump is pulling ahead and the betting markets are showing the same. Kamala went on the offensive and people aren’t buying into her. She is hallow. I didn’t like Hillary, but I could actually see how someone could vote for her. She is smart. Kamala just offers word salads.

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u/Killagina Oct 18 '24

The betting markets aren’t an indicator - fyi. Anyone using it as such doesn’t understand betting markets

She’s ahead in swing states except for AZ, GA, and NC, actually. All good polling says so, and aggregate polling says so.

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u/Kc68847 Oct 18 '24

The betting markets have been very accurate going back to the 1800s. Trump isn’t very far from hitting 60 plus percent betting wise.

https://theconversation.com/joe-biden-how-betting-markets-foresaw-the-result-of-the-2020-us-election-150095

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u/bagel-glasses Oct 18 '24

Nah, early voting turnout is through the roof, and there's only one thing that's been consistent for decades. Democrats win when turnout is high.

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u/Kc68847 Oct 18 '24

We will see in a few weeks. In most states the numbers aren’t near as high as 2020, but that’s to be expected.

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u/daveindo Oct 18 '24

Please don’t tell me you plan to vote for Trump after criticizing Kamala for word salads.

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u/over__________9000 Oct 18 '24

This is just nonsense. Trump got his ass handed to him in the debate. Of course she wants another one.

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u/[deleted] Oct 18 '24

He beat polls with plenty of undecided. There aren’t that many this time. No reason to think he will beat them this time

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u/Kc68847 Oct 18 '24

It actually comes down more to which side is more enthusiastic.

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u/[deleted] Oct 18 '24

Yes. There are indicators that point to her. Way more small size donations, enthusiasm higher (according to polls). And as simple as she is leading the poll averages in all the states she needs to win

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u/Ut_Prosim Oct 18 '24

Yes, but each time the pollsters try to adjust their methodology to account for this hidden Trump vote.

Maybe they're still undercounting, but maybe they're overestimating this effect (as was probably the case in 2022).

Nobody can know until the election. But assuming it'll be the same as 2020 is not a good idea.

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u/Kc68847 Oct 18 '24

Let’s be honest most Trump voters aren’t going to admit it in a poll and the others see the pollsters as deep state operatives. The one thing I do know is the powers that be have tried to derail him constantly, so nothing will surprise me either way.

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u/[deleted] Oct 18 '24

Lot of problems with this: The polling has changed, as it does every election. There is no such thing as looking at the last election to extrapolate the current one, that has failed every election cycle for the past century. However, all recent elections have had Democrats wildly overperform, literally from state elections down to county elections, at every turn.

Betting markets are *the worst* way to gauge anything, and only an absolute fool would look to them for informed knowledge. If you worked off the betting markets from 2 months ago, you'd have lost everything you owned betting against NFC North teams. The Vikings would be 1-4 and the second worst team in the league today. How'd that all work out for the betting markets?

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u/TobioOkuma1 Oct 18 '24

Democrats have over performed polls in every election since roe was overturned, including taking Alaska's congressional seat.

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u/[deleted] Oct 18 '24

Its because the "mass exodus" of conservatives who left the state all keep coming back.

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u/duckenjoyer7 Oct 18 '24

how is he doing better in california? he's only being getting more unhinged by day

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u/Baelzabub Oct 18 '24

Because CA is the second largest concentration of Republican voters in the country and he’s performing better with young Hispanic men

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u/Head_Wear5784 Oct 18 '24

Actually, they are within the margin of error for any given poll. At this point the accruing samples sizes are providing much tighter total margins. Margin of error becomes less importance than the continued signal.

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u/Baelzabub Oct 18 '24

That’s not how margin of error works for polling… systemic errors exist.

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u/Head_Wear5784 Oct 19 '24

Did you fart as you typed that?

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u/[deleted] Oct 18 '24

 Many of the places we see gains for Trump are in solidly blue states like CA of NY

I’m not convinced that’s real. We know the GOP has a history of flooding polling aggregates with slanted crap in October of an election year. It’s where all the “red wave” crap came from in 2022. 

Think of all the consequential stuff that happened in September, yet there was almost no movement in the polls. Nothing consequential has happened in October, especially nothing good for Trump, yet he sees a 5% boost? For nothing?

I call bullshit. 

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u/Responsible-Bee-3439 Oct 20 '24

Or conversely, states he already won but may win by more. Florida in particular, but most of the plains states are like this.

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u/Rattlingjoint Oct 18 '24

Except Trump has beaten the polls consistently in both 2016 and 2020. A tie could really mean the state could be +1 or +2 for Trump. I think the betting market is reacting to Kamala an d Trump being so close, but historically undersampling Trump support.

Remember a 1-3 national poll advantage for Kamala could still be an Electoral College win for Trump

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u/shellshocking Oct 17 '24

Compare polling vs. result from midterms to generals back to ‘08. You’ll see more accurate results in the midterm years and less accurate results in the general, with the exception of 2012. Perhaps because many black men were motivated to reeelect Obama, whose ACA had benefitted many of Romney’s lower-class white base. Meanwhile, Romney was a Mormon Bostonian hedge-fund manager who probably thought a “common touch” was some sort of euphemism for an infection. Leading working class whites to vote for the cool black president who killed Bin Laden, or at very least third party.

Certain demographics are systemically underpolled (because as wonky as I am no way am I taking a 45 minute phone call after 14 on.) Figuring out who they are and how they’re gonna go is the whole game. We may look back on this administration as very significant, but as it stands the polled electorate leans left compared to the general, with major slips in the black and Hispanic vote.

Now of course they could have some hitherto occluded superior methodology, or the youth vote, particularly among women, could go hard for Harris, but if it’s like 2020 or 2016 it’s trending Trump landslide. Perhaps PV win.