Princeton Election Consortium

A first draft of electoral history. Since 2004

Looking ahead

November 9th, 2016, 12:53am by Sam Wang


Going into today’s election, many races appeared to be very close: 12 state-level Presidential races were within five percentage points. But the polls were off, massively. And so we face the likelihood of an electoral win by Donald Trump. At the same time, Hillary Clinton appears likely to win the popular vote. The Upshot’s model currently projects a Clinton lead of a bit more than 1 percentage point. If that lead lasts, it means that more American voters preferred her to Trump.

At the moment, the NYT is projecting Trump leads of less than 1 percentage point in Pennsylvania and Michigan. Even without these states, Trump has at least 268 electoral votes (depending on some districts in Maine and Nebraska). We will see in the morning how these last few states and districts will be resolved.

In addition to the enormous polling error, I did not correctly estimate the size of the correlated error – by a factor of five. As I wrote before, that five-fold difference accounted for the difference between the 99% probability here and the lower probabilities at other sites. We all estimated the Clinton win at being probable, but I was most extreme. It goes to show that even if the estimation problem is reduced to one parameter, it’s still essential to do a good job with that one parameter. Polls failed, and I amplified that failure.

This election is about to create shock waves that will make the last year of campaigning look mild. We are about to see both houses of Congress under Republican control, quite possibly with a President Donald Trump. This comes in the face of a reasonably growing economy and a popular Democratic President.

Thinkpieces that have been written in the last few weeks have to be re-examined in a new light. Ezra Klein at Vox has written about the weakness in U.S. democracy, in which a weak Republican Party could nominate Trump, and partisan polarization gave him a shot at the Presidency. This one-two punch appears to have landed, hard. I was correct in documenting Trump’s rise in the primaries, an easier task for polling analysis because there, his lead was considerable.

I have written about the role of partisan polarization in getting voters to choose up sides, to the exclusion of even considering a vote for the other side. The chickens have now come home to roost. Exit polls showed that most voters felt that Trump lacked the temperament to be President, and that Clinton was seen as more qualified. Yet Trump seems to have rallied enough support to get overcome these factors. All Presidential nominees have had lower and lower approval ratings, and Clinton was no exception to the pattern.

Now we see where that long trend has led. One consequence is that more voters refused to support either major candidate. Neither Trump nor Clinton is headed for winning a majority of voters in Pennyslvania or Michigan. In Pennsylvania, the NYT projects that over 3% of voters cast their ballots for Gary Johnson or Jill Stein. In Michigan, the minor-party total was over 4%. In both cases, these numbers are considerably greater than the Trump-Clinton margin.

The coming years will be disruptive ones, to say the least. Whether you are Democrat, Republican, or neither, it’s going to be a challenging time ahead. It’s Donald Trump’s Republican Party, and maybe his Presidency too. The nation belongs to all of us. Good night.

→ 41 CommentsTags: 2016 Election · President

Election thread #2

November 8th, 2016, 9:34pm by Sam Wang


11:44pm: The business about 65%, 91%, 93%, 99% probability is not the main point. The entire polling industry – public, campaign-associated, aggregators – ended up with data that missed tonight’s results by a very large margin. There is now the question of understanding how a mature industry could have gone so wrong. And of course, most of all, there is the shock of a likely Trump presidency. I apologize that I underestimated the possibility of such an event.


11:12pm: Using the projections of the NY Times, Donald Trump is outperforming his pre-election polling margins by a median of 4.0 +/- 2.6 percentage points (the 8 states in the Geek’s Guide). In Senate races, Republicans are outperforming by 6.0 +/- 3.7 percentage points. A five-percentage-point polling miss would be a tremendous error by modern polling standards. Undecided or minor-party voters coming home to Trump? Shy Trump voters? I don’t know.


10:38pm: At the Senate level, the polling error is looking pretty substantial at the moment, maybe 5 points toward Republicans. A polling error of this size would be the largest on record, at least in a Presidential year. I was wrong to downplay this possibility.

We still have to see what will happen at the top of the ticket. But obviously, with a Meta-Margin of only 2.2%, an equally large across-the-board polling error at the Presidential level would suggest a Trump win of the Electoral College.


9:31pm: NYT presidential tracker showing things very close. Looks like a late night. And perhaps bug cookery for me.

→ 148 CommentsTags: 2016 Election

Election liveblog thread #1

November 8th, 2016, 6:14pm by Sam Wang


I’ll comment as the evening progresses.

9:09pm: The NYTimes Senate projected margins are running several percentage points more Republican than pre-election polls.

9:04pm: Here are some negative signs for Democrats: Trump’s ahead in Florida, overperforming his polls by several percentage points. Also, NH and PA Senate races leaning R at the NYTimes tracker.

I note that the generic House ballot swung toward Republicans by several points in the closing weeks, to D+1%. That is another piece of data suggesting that the GOP might overperform their polls. Definitely some mixed signals tonight.

8:43pm: Oh, this is awesome: the NY Times projection tool. So much better than TV. For now, it looks like control may come down to the New Hampshire and Pennsylvania Senate races. If Republicans take one of those, then they are likely to retain control. [Read more →]

→ 68 CommentsTags: 2016 Election · House · President · Senate

Geek’s Guide To The Election, 2016

November 8th, 2016, 12:00pm by Sam Wang


Here’s an informal guide to help you track results. I’ll probably update it up until 5:00pm. Please report errors in comments. Also, please list places you’ll be monitoring results tonight.

In other news, Buzzfeed has announced criteria for scoring the forecasters. They are using Brier scores and root-mean-squared errors.

Geek’s Guide Version 2.1, 2:00pm: Word and PDF. [Read more →]

→ 71 CommentsTags: 2016 Election

Final Projections: Clinton 323 EV, 51 Democratic Senate seats, GOP House

November 8th, 2016, 12:45am by Sam Wang


(Updates: 6:06am data for Presidential and Senate, and added confidence intervals. 9:00 am: more description, also variance minimization.)

Here are the final snapshots. Four Senate races are within one percentage point: Indiana, Missouri, New Hampshire, and North Carolina. Partisans there may want to lawyer up for possible recount battles.

Soon I’ll put out a brief Geek’s Guide to the Election. Also, live blogging starting around 8:00 pm. [Read more →]

→ 167 CommentsTags: 2016 Election · House · Senate

Today on The Takeaway: The Home Stretch

November 7th, 2016, 8:33am by Sam Wang


Today on The Takeaway with host John Hockenberry: How certain is the Presidential race? What about the Senate? Who picks the bug? The show airs nationwide at various times starting at 9:00am Eastern (I’m scheduled at 30-40 minutes after the hour). Find a radio station near you, stream at thetakeaway.org, or listen to the segment here.

→ 83 CommentsTags: 2016 Election · President · Senate

Is 99% a reasonable probability?

November 6th, 2016, 11:31pm by Sam Wang


Three sets of data point in the same direction:

  • The state poll-based Meta-Margin is Clinton +2.6%.
  • National polls give a median of Clinton +3.0 +/- 0.9% (10 polls with a start date of November 1st or later).
  • Early voting patterns approximately match 2012, a year when the popular vote was Obama +3.9%.

Based on this evidence, if Hillary Clinton does not win on Tuesday it will be a giant surprise.

There’s been buzz about the Princeton Election Consortium’s win probability for Clinton, which for some time has been in the 98-99% range. Tonight let me walk everyone through how we arrive at this level of confidence. tl;dr: With a more conservative assumption (see discussion) the PEC approach gives a probability of more like 95%. [Read more →]

→ 163 CommentsTags: 2016 Election · President · Senate

The Nevada bonus is back

November 6th, 2016, 10:17am by Sam Wang


Two states are hard to poll accurately, probably because they have high rates of migration: Alaska and Nevada. In addition, Nevada has a high Hispanic population, which votes heavily Democratic. Based on early voting, it looks like 2016 will be a repeat of 2010 and 2012, in which Democrats outperformed Nevada polls by 10 and 3 percentage points, respectively. [Read more →]

→ 107 CommentsTags: 2016 Election · Senate

Confidence is associated with increased turnout

November 5th, 2016, 10:40pm by Sam Wang


I’m getting mail claiming that when voters are sure their candidate will win, they are less likely to vote. Therefore (these are Democrats writing) I should pipe down. However, this speculation contradicts both human nature and empirical evidence. [Read more →]

→ 86 CommentsTags: 2016 Election · President

Beyoncé and Me

November 5th, 2016, 5:56am by Sam Wang



Well, this was unexpected. The clip is here.

→ 125 CommentsTags: 2016 Election · President · Senate