Princeton Election Consortium

A first draft of electoral history. Since 2004

A change in the air?

September 29th, 2014, 11:58am by Sam Wang

The Princeton Election Consortium’s approach to tracking current conditions has unique advantages, which are sometimes underappreciated and misinterpreted – even by major media figures. The advantages are:

(1) We have remarkably low noise compared with a simpler approach such as at or RealClearPolitics; and

(2) We have sharper time resolution than other sites that use smoothing, whether explicitly or implicitly, to get a more gradual curve over time. Those approaches can’t capture sharp changes as easily. Sites that appear to do this include HuffPollsterThe Upshot, and FiveThirtyEight.

Each site has its own advantages. The unique advantage of PEC’s Meta-Analysis is that it resists outliers – yet also captures real change. In other words, we publish a sensitive and accurate “electoral thermometer.”

In the last 10 days, that thermometer ticked sharply in the Republicans’ direction, past where it’s been at any point this election season. It is not time for Democrats to panic – especially since polls don’t always match final outcomes, even in the home stretch. However, it is time to choose battles carefully. At the end of this piece I will suggest some battles to choose. [Read more →]

→ 37 CommentsTags: 2014 Election · Senate

Midterm traffic – thank you

September 27th, 2014, 9:36am by Sam Wang

Some of you are asking if the PEC polls-only prediction is wrong. I say no: the prediction is OK…so far. Recall the central assumption: the Meta-Margin range from June through now is representative of the future. Obviously, this week it is on my mind that the assumption won’t hold up. However, we’re only a touch below the range I have stated: R+0.2% to D+2.5%. We’ll see very soon. Also, next week, as planned from the start, the PEC model will start incorporating an element of “random-walk-from-the-present.” At that point, any inaccuracy will tend to fix itself – like the other predictive sites.

In the meantime…thank you for reading, both here and at The New Yorker. The Princeton Election Consortium is getting excellent midterm traffic! We’re not far below the level for August-September 2012, which is pretty good considering it’s not a Presidential year.
As you might guess, last week’s dust-up created more traffic…though not that much direct linkback from our friends at the ESPN subsidiary.

In the meantime: watch the banner above, ignore isolated polls, and use the right sidebar…including ActBlue (Dems) and the NRSC (GOPers)!

→ 36 CommentsTags: 2014 Election · Senate

Alaska and Colorado on the move

September 26th, 2014, 3:57pm by Sam Wang

The Meta-Margin is a powerful statistical measure. It collects all available polls into a simple index that tracks movement in the national campaign. No house effects, no fancy stuff – just a measure of national opinion, calibrated using Senate control to define the zero point.

Recall that the Senate Meta-Margin is defined by how much all Senate races would have to swing together in order to create a perfect tied probability for Senate control between Republicans and Democrats+Independents. Yesterday, the Meta-Margin moved by 1.4% toward Republicans. By the standards of this year’s campaign, that is a huge movement. The change was mostly caused by movement in just two states, Alaska and Colorado. Those were ways for Democrats+Independents to hold 50 votes, and as of today, those routes are currently looking unfavorable. Therefore now the Meta-Margin is R+0.1%. That is a near-perfect tie if polls are exactly calibrated to Election Day behavior (is it? that’s a question for another day).

Our time window is currently to take the last 3 polls or the last 2 weeks of data, whichever is more, for each state. This measure takes a little while to move, but when it does, that’s meaningful. Statistically, we are now at the most Republican-leaning end of the range that we have seen in the entire graph.The dip in June looks better for Republicans, but keep in mind that on September 3rd, the Meta-Margin jumped by 0.8% when Chad Taylor (D-KS) dropped out of the race. Subtracting that gives a better feeling for where we’re at, not counting Kansas. In short: as a group, Republican Senate candidates outside Kansas are at an all-time high.

Will this change stick? There is still plenty of time for movement in most of the races listed in the right sidebar (The Power Of Your Vote). Still, we should take the latest change fairly seriously. Alaska was a hidden bonus for Republicans all along, as I analyzed yesterday. But the change in Colorado polls – I’ve been pondering that all week. Something big happened there: a swing from Udall +3.0±0.7% (mean±SEM, 4 polls) to Gardner +4.5±2.2% (4 polls). As a trigger, I nominate the Udall-Gardner debate, which is the kind of event that can move opinion by showing the two candidates side by side.

As usual, recall that The Power Of Your Vote is a list of states where individual votes are most valuable. Those states are where get-out-the-vote activism and campaign contributions will have the greatest impact.

→ 18 CommentsTags: 2014 Election · Senate

Brief update

September 26th, 2014, 8:45am by Sam Wang

In current polling conditions, the Senate Meta-Margin has left Democratic territory for the first time since mid-August. Not much to say about that for now, except that the sharp movement was driven by fresh polls in Alaska and Colorado. If you  have questions, read about Meta-Margins here.

The prediction is described here; it integrates information from June until now. If current conditions persist, it will start to move. Also, starting next Tuesday it will start to emphasize current conditions more, as those conditions start to be more strongly predictive of Election Day. More later.

→ 6 CommentsTags: 2014 Election · Senate

What’s The Real Source Of Inaccuracy In Alaska?

September 25th, 2014, 5:30pm by Sam Wang

On Tuesday, I suggested that control of the Senate could come down to as few as four key races in Colorado, Iowa, Louisiana, and Arkansas. There’s a fifth state where voters are exceptionally powerful: Alaska, because of the closeness of the race and its small population. But even though get-out-the-vote efforts in Alaska are certain to be valuable, activists will have to do their work without a clear picture of which candidate is ahead, Democrat Mark Begich or Republican Dan Sullivan.

As you can see, the Meta-Margin moved toward Republicans today. This is caused by two recent polls in Alaska. This race has had only seven surveys since Sullivan clinched the nomination in August. I think we may continue to see fluctuation in Alaska surveys in the coming weeks. Today I want to point out some special characteristics of Alaska that complicate any exercise in poll aggregation: its small population and extreme mobility in and out of the state. The bottom line is the possibility of polling error like what happened in the Nevada 2010 Senate race…though in the opposite direction. [Read more →]

→ 13 CommentsTags: 2014 Election · Senate

Register to vote **now**!

September 25th, 2014, 6:30am by Sam Wang

Comments OffTags: 2014 Election

Podcast at Political Wire

September 24th, 2014, 5:53pm by Sam Wang

I was interviewed today by Political Wire. Here it is!

→ 7 CommentsTags: 2014 Election

A change to the banner

September 24th, 2014, 12:01pm by Sam Wang

We’re trying out a change in the banner above. Previously, we showed a snapshot, i.e. what would happen in an election held today. Now, the only probability given is for Election Day. Why are we doing this?

The basic reason is that the election is not today. The day-to-day snapshot is extremely important because we use it to build a statistical model of the Senate race’s ups and downs. However, fluctuations in the probability tend to get people overexcited.

If you want to know about current conditions, focus on the seat count and the Meta-Margin. If you still want a current snapshot probability, you can still get it by clicking on the histogram at the right, which shows current conditions based on the most recent polls.

→ 8 CommentsTags: 2014 Election · Senate

And Then There Were Four (or Five?)

September 23rd, 2014, 1:06pm by Sam Wang

In the last few days the Meta-Margin’s been bouncing around. It’s a snapshot of current conditions, and will probably keep moving up and down. That bounciness – so vexing to some of you! – is part of how I am sampling day-to-day variation. This is the principal input to our predictive model for the November election.

For a more long-term look, see my new piece in The New Yorker. It details how the battle for Senate control has begun to focus strongly on four states (Arkansas, Colorado, Iowa, Louisiana) and maybe a fifth (Alaska) – and what activists are likely to do to sway the outcome in those races. Those activists might also be interested in the NRSC (Republican) and ActBlue (Democratic) links at the left.

Update: Back in July, I wrote a piece here at PEC with a very similar title. I am interested to see that three of the four states have not changed, though Kentucky (then) has been replaced with Arkansas (now).

→ 26 CommentsTags: 2014 Election · House · Senate

Weekend Nerdery (Basic level, part 1): Make Your Own Senate Prediction!

September 20th, 2014, 11:15am by Sam Wang

Some of you may think that analyzing polls is some kind of wizardry. It’s not.

This is the first of a few Basic posts. I’ll have Advanced posts too for extreme PEC aficionados. As always, I reserve the opportunity to make minor corrections. [Read more →]

→ 37 CommentsTags: 2014 Election · Senate