Princeton Election Consortium

A first draft of electoral history. Since 2004

Politics & Polls #22 with Linda Greenhouse: How will a Trump Presidency affect the Supreme Court?

December 4th, 2016, 3:26pm by Sam Wang

A new episode of Politics & Polls: How will a Trump Presidency affect the Supreme Court? And how soon? Julian Zelizer and I talk it over with veteran Supreme Court reporter Linda Greenhouse. Listen!

→ 6 CommentsTags: 2016 Election · President

Princeton Events – What Happened In The Election?

November 26th, 2016, 2:27pm by Sam Wang

This week at Princeton, I’ll be at two events to discuss what happened in the election, and the uncertain road ahead. Both are open to the public.

Monday November 28th, at 7:00pm. At the Princeton Public Library, I’ll join a panel moderated by Stan Katz, and featuring Ruth Mandel and Charles Stile.

Thursday December 1st, at 6:00pm. In McCosh Hall room 50 on the Princeton University campus, I sit down with Jamelle Bouie, chief political correspondent of Slate magazine. Bouie has written remarkable pieces about the Trump campaign and its relationship to race and politics in America. Here’s one. I look forward to a great discussion.

If you have kids and can’t come out, you might find this relevant: Talking to Young Children about the Presidential Election.

→ 12 CommentsTags: 2016 Election

Helping the New Gerrymandering Standard Survive in the Supreme Court

November 24th, 2016, 10:20pm by Sam Wang

Thanksgiving brings the nation a win for fair representation, in the form of a way to deal with partisan gerrymandering. A three-judge court ruled that the Wisconsin state legislative map is a partisan gerrymander: a map drawn to favor one major political party over the other (decision: Whitford Op. and Order, Dkt. 166, Nov. 21, 2016). The court applied a mathematical standard created by Nicholas Stephanopoulos and Eric McGhee, the “efficiency gap.” The case is now headed for consideration by the Supreme Court.

If this standard, or another that addresses the same need, is adopted widely, it would resolve a major gap in election law. This is an important case: In this year’s House elections, Democrats would have had to win the popular vote by at least 9 percentage points to take control. That is the largest partisan asymmetry on record. It would be reduced considerably if districting were done according to principles that treated both parties equally.

Let me outline the state of play and some potential weaknesses in the proposed standard. As an additional approach, I have developed two standards, based on longstanding statistical practice, which could help overcome skepticism by the Supreme Court. My standards can be calculated automatically at, and are described in detail in the Stanford Law Review. [Read more →]

→ 17 CommentsTags: House · Redistricting

On CNN around 9:25am Eastern w/Smerconish

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

Post-mortem. Plus, I keep my word about the bug.

→ 83 CommentsTags: 2016 Election

Politics & Polls #20: What Just Happened?

November 11th, 2016, 2:51pm by Sam Wang

Despite the importance of understanding this week’s cataclysmic events, I have been slow to write. There are other demands, especially my annual national scientific conference, which begins tomorrow.

The question of what went wrong in polls – and where I went additionally wrong – is an important one. I owe you a serious assessment, but it is not a topic to write about quickly.

This is a wrenching time in national politics. Most supporters of both Donald Trump and Hillary Clinton were surprised by the outcome. As Harry Enten at FiveThirtyEight points out, voters were more partisan than ever, with amazing party loyalty. Despite the few key upsets in close Rust Belt races, voting patterns are nearly identical to 2012. The state-by-state correlation between Romney-Obama and Trump-Clinton is +0.95 – right in line with post-Gingrich polarization.The parties are now fighting over mobilizing and turning out their own voter demographics.

In Politics & Polls #20, Julian Zelizer and I react to the results in episode #20, our first post-election recording. Among a host of issues, we discuss why the polls might’ve been off and what a Trump presidency means for the nation and possible implications for our democracy. Listen.

→ 76 CommentsTags: 2016 Election

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 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 (also known as the systematic 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 about to exit the White House. It is difficult to reconcile these different facts.

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.

→ 282 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.

→ 160 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 →]

→ 72 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 →]

→ 72 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 →]

→ 168 CommentsTags: 2016 Election · House · Senate