Princeton Election Consortium

A first draft of electoral history. Since 2004

Election Night liveblogging, 7:00PM

November 4th, 2014, 7:09pm by Sam Wang

See below the fold for older commentary. The most recent comment will appear up top.

8:40pm: The Upshot has projected counts. For now, use those for your Geek’s Guide. Shaheen (D-NH) around +5% and McConnell (R-KY) around +13%, both ahead of their pre-election polls. Ambiguous for estimating Delta.

8:27pm: Reader Forrest asked me how The Upshot estimates vote share from partial returns. I can’t say what they are doing, but look at Jay Boice’s HuffPollster calculation. Basically take the prior history of the state, county by county (or whatever level of granularity you have available). Then slide over all the counts in past comparable elections, and see how each county would have to break in order to reach a 50-50 tie. Use that as an over/under, i.e. calculate whether a candidate is over/underperforming that expectation. Then do a weighted average across counties. That is an estimator of the margin between candidates. [Read more →]

→ 84 CommentsTags: 2014 Election

Errors Are Inevitable – But Who Will Benefit?

November 4th, 2014, 2:00pm by Sam Wang

Despite the certainty of pundits, we actually don’t know who will win the Senate! In The New Yorker, I explain.

From 2004 to 2012, only thirteen Senate races have had margins of less than three percentage points in the week before the election. Of these, four were won by the trailing candidate. One more, the Florida 2004 race, was tied in the polls, and was eventually won by the Republican, Mel Martinez, by 2 percentage points. Scoring that one as half correct, the overall rate of wins by a front-runner is 65%, a bit better than chance.

In light of that, the probability that all six close Senate races (AK, CO, IA, KS, NH, and NC) will be won by the candidate in the lead is only 7%. A wrong call is almost inevitable. We should not be surprised to see one to three races to be won by the candidate who trails this morning. This allows us to hazard a guess as to the most probable path to Democratic retention of the Senate (which PEC currently has at 35%). [Read more →]

→ 38 CommentsTags: 2014 Election · governors · Senate

Geek’s Guide To The Election, 2014 edition

November 4th, 2014, 12:00pm by Sam Wang

Download it! It includes instructions for estimating Delta. Liveblogging will start around 8:00pm.

Useful links (will add as day goes on):
HuffPollster: Senate Election Live-Tracker.
DailyKos Elections, hour-by-hour guide.
New York Times, The Upshot, Senate tracker.

→ 4 CommentsTags: 2014 Election · governors · Senate

Senate and House final snapshots, 2014

November 4th, 2014, 1:54am by Sam Wang

Here are final polling snapshots for Senate races:
Put your own predictions in comments! Some more notes… [Read more →]

→ 91 CommentsTags: 2014 Election · Senate

Gubernatorial final snapshots, 2014

November 4th, 2014, 12:54am by Sam Wang

Here are final polling snapshots for gubernatorial races that are either close or likely to switch party control:

Put your own predictions in comments! Some more notes… [Read more →]

→ 20 CommentsTags: 2014 Election · governors

Grading policies

November 3rd, 2014, 8:33pm by Sam Wang

How should PEC be graded? As the last few polls trickle in, let me give a suggestion for how to evaluate predictions after the election. Late tonight I’ll give actual predictions (and give you a chance to record your own predictions).

My preferred measure is the Brier score. As I explain this concept, I’ll refer to some suggestions from FiveThirtyEight and Drew Linzer. [Read more →]

→ 14 CommentsTags: 2014 Election

Reality check: Obama net approval/disapproval

November 3rd, 2014, 7:00pm by Sam Wang

Coming into the home stretch, President Obama’s net approval/disapproval rating is at minus 8%. Not good…but 4% better than June. This is what candidates face as in-person voting starts tomorrow morning.

→ 8 CommentsTags: 2014 Election · House · Senate

Hidden errors, overconfident pollsters?

November 3rd, 2014, 10:05am by Sam Wang

I am thinking about how to get the most accurate last-minute snapshots of races, and how to turn that into a scorecard for you (and me) to use on Election Night. I’m also thinking about Brier scores as a means of evaluating the various prognosticators, including me.

In the meantime, here’s your morning reading: an excellent analysis by David Rothschild, Sharad Goel, and Houshmand Shirani-Mehr on the problems endemic to current polling practice. They analyze 2012 in great detail, and identify errors that go well beyond sampling error. Because these errors are unlikely to have been fully corrected this year, they think there’s a good chance that Democrats will outperform poll aggregates. In other words, all poll aggregators, including PEC, might carry a hidden bias. My own view is that based on historical data, errors have gone in either direction by several percentage points across the board. Go read their article!

→ 41 CommentsTags: 2014 Election · Senate

Late Breaks and Polling Biases

November 2nd, 2014, 12:00pm by Sam Wang

At least one journalist is chattering about whether there’s a late break in polls for Republicans…based on one data point, which is probably statistical noise. Some people are hopeless. Then again, several polls today have pushed the Meta-Margin almost as far as it’s been toward Republicans this campaign season.

He is missing a far more important point: Final election results can vary across-the-board from midterm polls – in the same direction. This last-minute polling bias is typically 2-3 percentage points – five times larger than the bias in presidential years. The direction of the bias is unpredictable. (Read this for a review of the subject.) This is why I care about the exact margins for front-runners McConnell (R-KY) and Shaheen (D-NH). Their states are early-reporting. From them we can make a rough estimate of nationwide polling bias, as follows. [Read more →]

→ 37 CommentsTags: 2014 Election · Senate

How To Get A Wave Majority With A Ripple Vote

November 1st, 2014, 10:15am by Sam Wang

New Yorker:
Republicans will probably win the national House popular vote, but even if they didn’t, it wouldn’t matter. Why not? In The New Yorker, I discuss gerrymandering (a big cause) and population patterns (a smaller cause).

→ 15 CommentsTags: 2014 Election · House