# Trump could win the election in a nowcast by FiveThirtyEight **URL:** \ **Category:** Politics & Elections\ **Created:** [July 25, 2016, 1:36pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846 "2016-07-25T13:36:00Z")\ **Posts on this page:** 20\ **Page:** 36
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 5:54pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/702 "2016-09-21T17:54:06Z")
Do the polls show a health bounce? Looking at 538’s polls-only national polling trend, I cannot discern one. Maybe there’s an inflection point around September 12, but it preceded the polling coming in with samples that included September 11. And if it’s an inflection point, it’s barely distinguishable from a half-dozen others in the slow creep going back to mid-August. Why isn’t the better analysis that Republicans are returning to Trump after a rough July? ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [September 21, 2016, 5:55pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/703 "2016-09-21T17:55:35Z")
> [@Richard\_Parker](#): > > Do the polls show a health bounce? Looking at 538’s polls-only national polling trend, I cannot discern one. Maybe there’s an inflection point around September 12, but it preceded the polling coming in with samples that included September 11. And if it’s an inflection point, it’s barely distinguishable from a half-dozen others in the slow creep going back to mid-August. > > Why isn’t the better analysis that Republicans are returning to Trump after a rough July? That’s possible too. We’ll see. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [September 21, 2016, 6:17pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/704 "2016-09-21T18:17:12Z")
Nate Silver [just tweeted](https://twitter.com/NateSilver538/status/778653379090325504) that there looks like a very small (1 point) shift in Hillary’s direction, nationally, in the last week. ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 6:19pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/705 "2016-09-21T18:19:44Z")
If you aggregate all the samples from those polls when calculating MOE, it’s _still_ probably bigger than net 1. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 6:32pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/706 "2016-09-21T18:32:59Z")
New Monmouth poll, rated A+ by 538, just came out putting Clinton +5 in Florida. Taken Sep 16-19th, making it well post 9/11 collapse and pre-Trump Institute shenanigans story. I know, I know. Don’t get worked up about individual polls. ---
**Author:** ![Jonathan\_Chance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jonathan_chance/32/701_2.png) [@Jonathan\_Chance](https://boards.straightdope.com/u/Jonathan_Chance)\ **Post date:** [September 21, 2016, 6:43pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/707 "2016-09-21T18:43:44Z")
It’ll be interesting to see what that does to the FLA map. 538 rates Monmouth A+ and adding a +5 to this: 9/14 Clinton +1 9/9 Clinton +2 9/12 Trump +3 9/7 Tie Should be interesting. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [September 21, 2016, 6:44pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/708 "2016-09-21T18:44:47Z")
I don’t think the Monmouth FL poll is brand new – I think it was already worked into 538. And I think it’s the one I was thinking of earlier, not the St. Leo poll. ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 6:49pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/709 "2016-09-21T18:49:30Z")
That’s correct. They put the Monmouth FL poll in yesterday. ---
**Author:** ![skdo23](https://avatars.discourse-cdn.com/v4/letter/s/a5b964/32.png) [@skdo23](https://boards.straightdope.com/u/skdo23)\ **Post date:** [September 21, 2016, 7:04pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/710 "2016-09-21T19:04:53Z")
Does anyone know anything about St. Leo? Judging from the adjustments made 538 seems to believe they’ve been leaning overly blue, but do they have any type of history that makes them reliable once adjusted? ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 7:29pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/711 "2016-09-21T19:29:34Z")
> [@Richard\_Parker](#): > > That’s correct. They put the Monmouth FL poll in yesterday. I guess I have to just trust him but it’s weird; on the Florida polling: - his “adjusted” number for A+ rated Monmouth, with a “mean reverted bias D+.9”, moves it from Clinton+5 down to Clinton +4 - but his “adjusted” number for A rated Siena, with a “mean reverted bias R+.3”, moves it from Clinton +1 to Trump +1. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 7:37pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/712 "2016-09-21T19:37:38Z")
Edit:Sorry, Monmouth is only D+.6 ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 7:38pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/713 "2016-09-21T19:38:30Z")
> [@CarnalK](#): > > I guess I have to just trust him but it’s weird; on the Florida polling: > > - his “adjusted” number for A+ rated Monmouth, with a “mean reverted bias D+.9”, moves it from Clinton+5 down to Clinton +4 > > - but his “adjusted” number for A rated Siena, with a “mean reverted bias R+.3”, moves it from Clinton +1 to Trump +1. It has nothing to do with the pollster rating. It does involve house effects, but there are also a half-dozen other factors. They explain the methodology on the page, I think. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 7:44pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/714 "2016-09-21T19:44:25Z")
> [@Richard\_Parker](#): > > It has nothing to do with the pollster rating. It does involve house effects, but there are also a half-dozen other factors. They explain the methodology on the page, I think. But the adjustment is based on 538’s judgment of their bias, no? But for one poll there’s a full point adjustment against this percieved .6 bias and in the other there’s a two point adjustment in the same direction as this .3 bias. ---
**Author:** ![Rick\_Kitchen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rick_kitchen/32/522_2.png) [@Rick\_Kitchen](https://boards.straightdope.com/u/Rick_Kitchen)\ **Post date:** [September 21, 2016, 7:52pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/715 "2016-09-21T19:52:23Z")
538 today has Nevada as extremely pale pink, Florida as only slightly more pink, and North Carolina and Ohio as less pale pink, but still not red. Surprisingly, Rhode Island is only pale blue. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 7:56pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/716 "2016-09-21T19:56:19Z")
Sorry I meant to add, I know 538 also makes adjustments to “equalize” polls wrt likely voters/registered voters and 4-way/2-way but I think both of the ones I mentioned were the same in that respect. Basically, I am squinting hard at his adjustment of the Siena numbers. ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 8:01pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/717 "2016-09-21T20:01:59Z")
> [@CarnalK](#): > > Sorry I meant to add, I know 538 also makes adjustments to “equalize” polls wrt likely voters/registered voters and 4-way/2-way but I think both of the ones I mentioned were the same in that respect There’s also a “trend line adjustment,” and “house effects adjustment”–the latter being independent from the pollster’s rating. The trend line adjustment is described as follows: > [@](#): > > The model detects movement in the polls by making comparisons between different editions of the same poll. For example, if Clinton is at 46 percent in the Quinnipiac poll of Florida in August and was at 43 percent in the same poll in July, that suggests she’s gained 3 percentage points. Likewise, if Trump’s at 41 percent in the Rasmussen national poll this week and he was at 40 percent last week, that suggests he’s gained 1 percentage point. The model runs this calculation for Clinton, Trump and Johnson separately. It’s possible for all candidates to gain (or lose) votes from undecided. By making an apples-to-apples comparison, this method removes a lot of noise. > > Next, the model takes these comparisons and draws a trend line from them using loess regression. Polls are adjusted based on this regression. For instance, if Trump led in a North Carolina poll by 1 percentage point in June, but the trend line shows him having gained 3 percentage points nationally since then, the model will treat the poll as showing him up by 4 percentage points. This calculation varies slightly from state to state based on a state’s elasticity score. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 8:18pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/718 "2016-09-21T20:18:17Z")
The house effects adjustment, afaik however, is exactly what the mean reverted bias is about, which I already talked about. So we are left with the trendline adjustment being the sole culprit for a rather large difference in how these polls, taken within a week of each other, were adjusted. ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 8:29pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/719 "2016-09-21T20:29:32Z")
> [@CarnalK](#): > > The house effects adjustment, afaik however, is exactly what the mean reverted bias is about, which I already talked about. So we are left with the trendline adjustment being the sole culprit for a rather large difference in how these polls, taken within a week of each other, were adjusted. I don’t really understand your criticism. We have two polls. Assuming the “mean reverted bias” is the same as house effect, then we know that piece of the adjustment for each (.3R and .6D). Assuming the likely voter and third party adjustments are the same, and that neither poll reflects a convention bounce, that leaves trend line to explain the differential adjustments. The adjustments, breaking out the house effect, are: An additional 2.3 for Trump (9/10-9/14) An additional .4 for Trump (9/16-9/19) This implies that the trend line adjustment for 9/10-9/14 was +2.3 Trump, and the trend line adjustment for 9/16/9/19 was +.4 for Trump. Why do we think that’s wrong? Also note that they round the adjustment numbers, so the difference might be even smaller than it seems. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [September 21, 2016, 8:47pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/720 "2016-09-21T20:47:19Z")
Well I think it might be “wrong” because 2.3 is a lot more than .4 in this context, i.e. that the trendline is given such a weight as to give such different adjustments to polls taken within 10 days of each other. I’m sure he’s got more math on his side than me but it just strikes me as dubious. ---
**Author:** ![Richard\_Parker](https://avatars.discourse-cdn.com/v4/letter/r/35a633/32.png) [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)\ **Post date:** [September 21, 2016, 9:00pm UTC](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846/721 "2016-09-21T21:00:42Z")
With rounding artifacts, there could be less than a point difference between them, which doesn’t strike me as an obvious impeachment of the method since the polling periods didn’t even overlap. But I have to confess that I don’t really understand the trendline adjustment or why it’s beneficial. [Previous page](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846.md?page=35) [Next page](https://boards.straightdope.com/t/trump-could-win-the-election-in-a-nowcast-by-fivethirtyeight/760846.md?page=37)