538 Model Megathread

[Nym90]

If you sort the states by Trump's %chance to win, then NH is actually the tipping point at 32.8% vs 27.6% for VA. 

So Trump's narrow path ( sorted by % chance to win) is Romney + OH + CO + IA + FL + NH

Delving a little deeper he has a better chance of winning ME-02 (currently about 40% according to polls-plus) than most of those states. The really narrow Trump path would be Romney plus OH, CO, IA, FL and ME-02 which gets him to 269 EVs and then the GOP House majority elects him President (or would they?).

Realistically though, I doubt Trump would win Maine's 2nd district if he can't win New Hampshire, although there are reasons to believe the former could be more favorable to him than the latter since it's more rural.

[Nym90]

The reason Silver got the primaries wrong was because he was just winging it and had no model. You'll notice his models predicting each indvidual primary were quite good.

That's one of the big ironies of Trump's winning the nomination....the numbers were telling us ever since July of last year that he was the favorite, it's just that no one believed the data. In their defense though, early primary polls had quite often been wrong before, so there was good reason to be skeptical and think that Trump was another Herman Cain or Rudy Giuliani, but it's something to keep in mind. The polls this year have actually been more accurate than normal, which is the opposite of what your intuition might tell you about such an unconventional candidate as Trump.

[Nym90]

Perhaps Clinton going after NE-2 is their backup plan in case Trump wins ME-2. That would be pretty crazy outcome withe the race coming down to NE and ME and their weird rules.  You can bet the NE legislature would be kicking themselves for not going through with the idea of switching to WTA.

Makes sense, though the odds of it coming down to one EV are quite slim. But with a vulnerable incumbent D congressman in NE-02, it's definitely worth spending money there.

[Nym90]

Serious question - why does the Nowcast do a trendline? That doesn't make sense to me. If Clinton leads in Nevada now (as she does per their poll model) why would the Nowcast not predict her as ahead?

Maybe I'm misunderstanding something, but the latest 5 it's showing have Trump up in 3 and Clinton up in 1. The most recent is Clinton +4, but it gets adjusted to a tie based on other factors (e.g. national polling, covariance with other states). So I guess it doesn't surprise me.

If you look at the Nevada Nowcast it has a polling average of Clinton +1.5%.

Adjustment for some of their stuff brings it to Clinton +1.2%.

THEN they adjust for "trend" which swings it by 4.5% in Trump's favour and gives it as Trump +3.4%.

I don't get what trend they're adjusting for if it's "election held today". The net swing is roughly the same as in the forecasts for November 8th.

They are looking at how the national polls have changed since those Nevada state polls were conducted, and assuming Nevada has gone to the right at the same pace since then as the rest of the country (even though we don't have recent Nevada polls to confirm this).

[Nym90]

As I understand it, the difference between now-cast and polls-only is that polls-only assumes some regression to the mean between now and November, thus she is still ahead because it considers the polls more likely to move in Clinton's direction between now and then than it does Trump's. It also values higher quality, older polls (which were more favorable to Clinton) over lower quality, newer polls that favor Trump (you may notice that the more highly rated pollsters, wisely IMO, are avoiding polling between conventions).

Now-cast puts more of a premium on recent polls than on polls with a better track record, and assumes the election is today and thus no further movement can occur.

[Nym90]

I've noticed sometimes the forecast updates without a new poll being inputted; I would assume this is a fundamentals and/or timeline adjustment (fewer days until the election thus less uncertainty).

[Nym90]

He never thought Rhode Island was a swing state. That one poll showing Clinton up by only 3 (with no other polls showing otherwise) did cause Trump to have over a 10 percent chance of winning Rhode Island for a while, which while seemingly ridiculous given past results there, is probably about right given a lack of any other evidence.

That same pollster, Emerson, now has Clinton up by 20 in their latest poll, thereby "fixing" the Rhode Island odds.

[Nym90]

There is a way to check to see if he's right or not; if events that he says has x% chance of happening actually do end up happening x% of the time.

His predictions have ended up being quite accurate in that regard.

[Nym90]

Talk about polarization. Currently the polls-plus models for both President and Senate have every state with a Senate race voting for the same party for both offices. Every Clinton state voting for a Democratic Senator, and every Trump state for a Republican Senator.

[Nym90]

Based on polling, Clinton's odds in Alaska should probably be significantly higher, but remember that Alaska polling is awful.