538 Model Megathread

[rafta_rafta]

538 model is way too flexible this time around. Or it might just be the news cycle

[Xing]

North Carolina is now blue in the polls-only model. I remember some states swinging around a bit in 2012, but the amount even his polls-plus model has swung around is pretty insane.

[GeorgiaModerate]

North Carolina is now blue in the polls-only model. I remember some states swinging around a bit in 2012, but the amount even his polls-plus model has swung around is pretty insane.

There's been a lot more uncertainty in this election than there was in 2012, when the trend was pretty obvious (except to poll unskewers) for most of the election, except right after Romney's victory in the first debate.  The 538 models are bullish on uncertainty (to quote Nate) so they do react -- perhaps overreact -- to fluctuations in polling. 

[Attorney General & PPT Dwarven Dragon]

WELCOME HOME, NORTH CAROLINA!!!

[Mr. Morden]

I don't think the swings have been "insane" at all.  This is a pretty normal election as far as poll changes have gone.  2012 was an outlier for being so stable.

As far as this race goes, in the 538 polls-only model, there's been some drift of a few points back and forth around a Clinton lead of about 3 points.  But, newsflash: when the national popular vote margin changes by 2 points, it means that more than one or two states change from being favored by one party to the other.  That's how the electoral college works.  There are these close states that we call "swing states", and it doesn't take much movement in the national margin to switch them from one candidate to the other.

[Mr. Morden]

I feel like some folks here are convinced they "know" what Clinton's victory margin is going to be.  Like she's going to win by 4 points or 5 points or whatever.  And then when the polls match that number, it confirms their prior assumptions, whereas when the polls don't match that number, it's just a temporary blip, or some weird phenomenon with polling crosstabs or something like that.  They think that the 538 model should always "know" that the true margin is Clinton by 4 or 5 points or whatever, even though it's based on polls, and the polls don't always show that kind of margin.

But obviously if the polls move from Clinton +1 to Clinton +4 or whatever it is now, then the probabilities in the model will change more than a little.  What else are people expecting to happen?

[Xing]

My point is that I would expect a decent amount of movement in the polls-only and especially the now-cast models. I would think that the polls-plus model, however, would be a bit more static, especially in the probabilities it assigns to Trump or Clinton winning.

[Mr. Morden]

My point is that I would expect a decent amount of movement in the polls-only and especially the now-cast models. I would think that the polls-plus model, however, would be a bit more static, especially in the probabilities it assigns to Trump or Clinton winning.

Polls plus is still mostly based on polls though.  There are some "fundamentals" added in, but this close to the election, I don't think they count for very much.  In terms of predictive power based on quantitative observations, polls are a much stronger predictor of how the election is going to turn out than anything else out there.  And so, when the polls go from a tie to a 4 points Clinton lead or whatever it is now, it's going to make a big change in the probabilities.

Now, granted, maybe we can predict certain changes in the polls, and therefore be "smarter" than the model.  For example, we could predict that Clinton would have been more likely to gain in the polls from the debate than Trump, sure.  But how is a mathematical model supposed to "know" things like that?  Should we plug Clinton's and Trump's IQs into the model as extra parameters?

[Angel of Death]

Is North Carolina really going to vote to the left of Ohio and Iowa?

[BlueSwan]

Is North Carolina really going to vote to the left of Ohio and Iowa?

It is starting to look like it.

[ursulahx]

Is North Carolina really going to vote to the left of Ohio and Iowa?

I think the McCrory factor may play into this one. Plus a competitive Senate race, whereas Strickland has been hopeless in Ohio.

[Beefalow and the Consumer]

Is North Carolina really going to vote to the left of Ohio and Iowa?

Iowa might vote to the right of Arizona and Georgia.

[GeorgiaModerate]

Is North Carolina really going to vote to the left of Ohio and Iowa?

NC to the left of Iowa looks very likely.  I'm skeptical about it being left of Ohio.

[ProudModerate2]

If we get just one or two small Clinton leading-in-Ohio polls, then I suspect that 538 will flip Ohio to Hillary-blue in their "Polls-Only forecast" model.
It is so close to the tipping point right now (Oct 1st, 2pm Eastern), that anything positive for her should shift it in her favor.

[ursulahx]

If we get just one or two small Clinton leading-in-Ohio polls, then I suspect that 538 will flip Ohio to Hillary-blue in their "Polls-Only forecast" model.
It is so close to the tipping point right now (Oct 1st, 2pm Eastern), that anything positive for her should shift it in her favor.

That Selzer poll seems to be part of the problem.

[ProudModerate2]

If we get just one or two small Clinton leading-in-Ohio polls, then I suspect that 538 will flip Ohio to Hillary-blue in their "Polls-Only forecast" model.
It is so close to the tipping point right now (Oct 1st, 2pm Eastern), that anything positive for her should shift it in her favor.

That Selzer poll seems to be part of the problem.

True. It seems that 538 has classified it with so much weight (probably with its A+ rating).
But look at the date period that this poll covered .... Sept 9-12.
It is now getting old, so a new poll with a decent rating (and the like) will probably overshadow the Selzer numbers and take precedence.

[rafta_rafta]

Does Trump have a path without PA, VA and NC?

[GeorgiaModerate]

Does Trump have a path without PA, VA and NC?

It would be very tough (if he's already lost PA/VA/NC, winning all the other swing states would be like drawing to an inside straight flush) but this would get him to 270 exactly:

[ProudModerate2]

Does Trump have a path without PA, VA and NC?

rafta,
May I suggest that you visit and look at The New York Times, The Upshot, "Who will be President" analysis and tools.
Here is the link : http://www.nytimes.com/interactive/2016/upshot/presidential-polls-forecast.html?_r=0

Scroll down to the very bottom, and look at the section "Paths to the White House."
Hover your mouse over each of the check-marks, to get a reading on how each scenario might work. (PS: The larger the check-mark, the higher probability that that scenario will happen.)  The entire page has some neat information, so give it a look.

[Lachi]

Does Trump have a path without PA, VA and NC?

he MUST win all of these states in this scenario:
FL, OH, WI, CO, IA, NV, and NH

in other words, realistically no.

[rafta_rafta]

he MUST win all of these states in this scenario:
FL, OH, WI, CO, IA, NV, and NH

in other words, realistically no.

rafta,
May I suggest that you visit and look at The New York Times, The Upshot, "Who will be President" analysis and tools.
Here is the link : http://www.nytimes.com/interactive/2016/upshot/presidential-polls-forecast.html?_r=0

Scroll down to the very bottom, and look at the section "Paths to the White House."
Hover your mouse over each of the check-marks, to get a reading on how each scenario might work. (PS: The larger the check-mark, the higher probability that that scenario will happen.)  The entire page has some neat information, so give it a look.

It would be very tough (if he's already lost PA/VA/NC, winning all the other swing states would be like drawing to an inside straight flush) but this would get him to 270 exactly:

Thanks!

[Beefalow and the Consumer]

In the Now-Cast, Trump has a better chance in Delaware (11.6%) than in Virginia (11.1%).

lol?

[jaichind]

Looks like 538 entered the latest NM poll incorrectly.  They have it 45 31 24 when it should be 35 31 25.  The Clinton lead is 4 and not 14.

[rafta_rafta]

Looks like 538 entered the latest NM poll incorrectly.  They have it 45 31 24 when it should be 35 31 25.  The Clinton lead is 4 and not 14.

They fixed it now

[PaperKooper]

In the Now-Cast, Trump has a better chance in Delaware (11.6%) than in Virginia (11.1%).

lol?

Delaware's moving pretty far to the right since Biden and Obama won't be on the ballot.