538 model & poll tracker thread

[Fmr. Gov. NickG]

I’ve been predicting the NPV would be Biden +9 for three months now!

So the tipping point is 2.3 points to the right of the nation, compared with 2.9 points I believe in 2016.

Interesting that they project Biden to win CA by less than Hillary won it

[Fmr. Gov. NickG]

Based on his tweets about trying to model vote suppression, I get the feeling Nate has a completed model already, but that it came out looking way too confident in a Biden win for his liking, so he's trying to figure out how to include some additional doodads to make Trump look less hopeless.

[Fmr. Gov. NickG]

One side effect of these trashy national polls we've gotten the last two days is that Trump's electoral college advantage is down to 1.0% (Biden up 7.9% nationally vs. 6.9% in the tipping point state).

[Fmr. Gov. NickG]

Regardless of what you think about the model’s approach to uncertainty about the future, even giving Biden a 93% chance to win today seems low.

[Fmr. Gov. NickG]

How do you access the national polling average? 

The design of this pretty awful for those who are actualy trying to find the data.

[Fmr. Gov. NickG]

The model has now been out for a week, and the probabilities haven't really budged.   Biden's polling average lead has gone from 8.2 last Wednesday to 8.5 today, and his probability of winning has only gone from 71% to 72%.  But shouldn't the model be steadily becoming more confident over time even if the polls don't change much?

[Fmr. Gov. NickG]

It’s really bothersome how little information the design of this model makes easily available to viewers.  It seems like the only message they want to communicate is “I guess anything could happen?!?”.

Where’s the “polls only” forecast?
Where’s the “now cast”?
Where’s the easy link to the database of polls used to generate the projections?
Where’s the accounting for how individual “fundamentals” factors influence the projections?
Where’s the map??

All of this was available in the 2016 model, which actually performed quite well.  This is such a huge step backward.

[Fmr. Gov. NickG]

It looks like the latest Rasmussen poll has dropped Biden down to only being "slightly favored" in the race (which I suppose it their categorization for 60%-70%?).

I have a lot of problems with this model.  But while I think the bump today is pretty baseless, I don't really blame the model for it. 

A model that relies so heavily on polls is only going to be as good as the quality of the polls it has available to input.  We've only been getting garbage polls, and so it's understandable when it spits out garbage.  The blame lies in the lack of quality polling since the DNC.

[Fmr. Gov. NickG]

Don't talk to me about the race "tightening" until this changes:

[Fmr. Gov. NickG]

https://twitter.com/gelliottmorris/status/1298797791523868673?s=20

Certainly it’s not entirely reconcilable, but one factor to remember is that the conventions were a full month earlier in 2016, which would probably imply less uncertainty about the state of the race on this date in 2016.  But it does seem like Silver is just arbitrarily building more uncertainty into his model this year.

[Fmr. Gov. NickG]

I think the model must incorporate national polls somewhat, because Biden’s chances in every swing state dropped a point or two yesterday afternoon when the Rasmussen poll came out, even those that haven’t been polled in quite a while.

[Fmr. Gov. NickG]

IIRC, it includes national polling by creating a trend line. So if Biden loses a point from July nationally they adjust the state polls by a point (not exactly, because there is elasticity etc but basically)

This seems like basically the right way to incorporate national polls to me.

I don't fault them for not incorporating Trump's approval rating.  I -do- fault them for incorporating a number of other "fundamentals" that are really just there to artificially generate more uncertainty.

538 really should have just stood by their model from 2016.

[Fmr. Gov. NickG]

Biden keeps going up in the polls but down in the projections because look at these fonts!

[Fmr. Gov. NickG]

The model now shows decimals when you toggle the popular vote.

Current popular vote prediction is Biden 52.4 - Trump 46.3

Has anyone questioned Silver why his model takes for granted that the race will tighten?
I mean there are plenty of cases where the opposite happened.

It's not necessarily that he thinks the race will tighten.  He thinks the race will converge on the "fundamentals", and right now the "fundamentals" (especially I believe the stock market) predict a tossup race.

Right now, the predictions for each state are only 40-50% based on the polls, and 50-60% based on everything else Silver has decided might be relevant.

[Fmr. Gov. NickG]

The national polling average really dropped an *ENTIRE POINT* because of the Zogby poll. Really.

That MO Trafalgar poll also dropped a point off Biden's win %.

I assume this point mostly dropped off because of the Zogby poll, not the MO poll.  It's back to 69-31 now after the GQR PA poll and the Harris national poll, both showing Biden +9.  

In any case, Nate has tweeted that a 1% change can sometimes be the result of the model just drawing a different sample even if is given no new information.

And it's hard to fault the model for changing in response to trash polls when it is -only- given trash polls as inputs.

[Fmr. Gov. NickG]

I wouldn't expect a C-rated poll that is 1 point off the average to move the average at all.  Obviously a poll that is 4 points off the average is going to move it much more.

I would question why 538 seems to be interpreting the RMG result as Biden +4 rather than Biden +8.

[Fmr. Gov. NickG]

I think they've made a lot of questionable decisions with their model this year.
But their polling averages still seem pretty well designed to me.  It's not their faults we're only getting sh**tty polls right now.

[Fmr. Gov. NickG]

Biden's odds have bumped back up to 70% in the model today, but for some reason he's still listed as only "slightly favored".

[Fmr. Gov. NickG]

538 has added 13(!) distinct national polls to their database today.
Mean, median, and modal Biden lead are all 8 points.

[Fmr. Gov. NickG]

The new info on the state pages is actually pretty helpful.

It looks like the “economics and incumbency” portion always constitutes 18% of the projections right now, and basically always favors Trump.  I believe this portion will gradually decline to 0 as we get closer to the election.

Of the remaining 82%, it look pretty evenly split betwwen polls versus demographics on average, though it tilts in favor of polls in swing states with more polling.  Unlike the “economics and incumbency” factor, it doesn’t seem like the demographics factors consistently favors on side or the other.

In also looks like the model always allocated undecided voters exactly evenly.

[Fmr. Gov. NickG]

Given how important the “economic fundamentals” are to Nate’s model, I’m a little surprised that Biden hasn’t seemed to gain anything from the stock market crash over the past few days.

[Fmr. Gov. NickG]

Trump at 69% in the TX forecast, first time he's been below 70% since August 4.

Also, small thing, but I still can't get over how they have NM & VA (94/95% Biden) as "states to watch" but TX isn't considered one. Hell, they currently got Biden standing a better chance of winning MI/MN/NH/NV/PA/WI than Trump does of winning TX. How is it not a "state to watch"?

Where are you even seeing “states to watch”?  I see a list of “states with the closest races” (which Texas is on) and “states closest to the tipping point” (which TX is not on, but neither are NM or VA).

The 538 model of TX right now breaks down as a virtual tie in the polling average (56%), Trump +5 in the demographics (27%) and a whopping Trump +12 in the “economics and incumbency” fundamentals (17%).  Fortunately, the “economics and incumbency” party gradually declines to 0 as we get closer to the election, so Texas will also get much closer in the projection if the polls stay the same.

[Fmr. Gov. NickG]

I don't agree with his assessment. We've had 58 Presidential elections which is nowhere near enough to know how weird things could get if you could run this election 40,000 different ways. Heck just look at 2016 where a single sate Utah is about 20% less Republican than it should be given how the other states went.

Utah didn't vote 20% less Republican than it should based on the polls.  At this point in the 2016, there were several showing Trump with a very narrow lead in Utah.  So if the model came up with an output in which Utah voted Democratic, there was at least evidence to support this.  Trump actually outperformed his polls by a significant degree in Utah.   

By contrast, I'm not seeing any evidence whatsoever suggesting any strongly Democratic states have the potential to go rogue in this election.  And I can't even remember any huge shock results like this in the past.  Probably the biggest shock relative to PVI was Obama winning Indiana in 2008, and this too was predictable from the the polling by September.

[Fmr. Gov. NickG]

I don't agree with his assessment. We've had 58 Presidential elections which is nowhere near enough to know how weird things could get if you could run this election 40,000 different ways. Heck just look at 2016 where a single sate Utah is about 20% less Republican than it should be given how the other states went.

Utah didn't vote 20% less Republican than it should based on the polls.  At this point in the 2016, there were several showing Trump with a very narrow lead in Utah.  So if the model came up with an output in which Utah voted Democratic, there was at least evidence to support this.  Trump actually outperformed his polls by a significant degree in Utah.  

By contrast, I'm not seeing any evidence whatsoever suggesting any strongly Democratic states have the potential to go rogue in this election.  And I can't even remember any huge shock results like this in the past.  Probably the biggest shock relative to PVI was Obama winning Indiana in 2008, and this too was predictable from the the polling by September.

Sanders's win over Clinton in Michigan in 2008 was a 20 point swing from the polling that week.

Now I know you can give me reasons why that's different and why it won't happen this time (and yes I know it was the primary). The point is that shock results happen. And your guess is as good as mine at how likely a shock result in Oregon is if you give it a go 40,000 times.

I know the chance the model estimates of any one particular freak event happening is very small.

But it still seems like there is a category of freak event that the model collectively overestimates.  That is an election where one candidate wins in a national landslide, but the other candidate randomly wins a state that should be safe for the landslide winner.

I can’t off the top of my head think of a single historical example of this happening.  Nor can I think of a plausible explanation for why it might happen this year.  It’s not just that I think there is a less than a 1-in-40,000 chance that Biden wins in a landslide but loses New Jersey.  I think there is less than a 1-in-40,000 chance that Biden wins in a landslide but loses any deep blue state, especially given the Nate’s caveat that he is only attempting to model a reasonably free and fair election.

[Fmr. Gov. NickG]

I think there is less than a 1-in-40,000 chance that Biden wins in a landslide but loses any deep blue state

I don't agree with that, but obviously impossible to know either way. One way I can think that could happen is a last minute write-in campaign by someone really popular, focused in just one state, to make a point. I don't think Nate's model is predicting write-in campaigns, but I do think it sees Indiana and Utah (apparently) randomly swinging hard from one election to the next. That affects how it models the fat tail, and it should.

Yeah, I should probably clarify that I don’t think these scenarios are possible with the constraints of what the model is trying to model.  It seems to only be able to model scenarios in which Biden and Trump combine to win >95% of the vote.  But there is a much greater chance that some third party or write in candidate wins a relevant vote share than in which Biden win every state except New Jersey, and yet the model.

For example, the model currently includes a 1-in-100 chance that Trump wins California by >5 points, 52.1-46.9.   I could believe there is a measurable chance that Trump wins California by 5.  But it would only happen in a scenario where Biden died or dropped out or was so tarnished by a sudden scandal that a third-party candidate won 20%+ of the vote.  I believe the 52.1-46.9 scenario is basically impossible.