Political scientists predict Clinton will win 347 electoral votes

Asking experts to predict what is going to happen is probably one of the oldest forecasting methods available. When it comes to predicting election outcomes, we expect experts to have experience in reading and interpreting polls, putting them in historical context, and estimating the likely effects of upcoming campaign events. While the judgment of a single expert should be treated with caution, combining the opinions of several experts improves accuracy.

We have conducted expert surveys as part of the PollyVote project since its launch in 2004. In these surveys, we asked experts to predict the national popular vote. As shown in the chart below, their forecasts have always added valuable information and thus contributed to the accuracy of the PollyVote.  On average, adding expert judgment to the combined PollyVote reduced forecast error by 15%.

For this year’s election, we launched our first survey in December 2015. Since then, the experts’ average forecast always had Clinton in the lead, with a predicted share ranging from 52.2% to 55.5% of the major party vote, which excludes votes for third-party candidates. The latest survey conducted in late July predicted Clinton to gain 52.7%, compared to 47.3% for Trump.

Now, for the first time ever, we set out to conduct a state-level expert survey in order to predict the electoral college. For this, we reached out to political scientists across the country and asked for their help. After respondents revealed their home state, they had to answer two short questions:

  1. What share of the vote do you expect the nominees to receive in your home state?
  2. What do you think is Hillary Clinton’s chance of winning the election in your home state?

A total of 678 experts made estimates as requested. The number of experts by state ranged from one to 42. The table at the end of this post shows the number of respondents per state as well as the median answer for each question. We aim to recruit more experts in states with seven or fewer experts in future survey rounds.

Expert surveys don’t have to include many people to produce accurate forecasts. Prior research shows that eight to twelve experts are close to the optimum. For example, Polly’s survey of the popular vote has provided accurate forecasts with a sample of about twelve experts.

The map below shows Clinton’s chance of winning per state. This expert survey predicts that Hillary Clinton will win 347 electoral votes, compared to 191 for Donald Trump. This forecast is in line with those from Daily Kos, NYT Upshot, PredictWise, Sabato, and the combined PollyVote.

Experts’ Electoral College forecast

Overview of results

Clinton’s predicted
State N Chance of winning Two-party vote
District of Columbia 18 100% 94.6
Vermont 11 99% 66.7
New York 24 99% 64.2
Massachusetts 11 99% 66.7
Maryland 26 99% 63.6
California 24 99% 62.2
Illinois 27 98% 60.4
Washington 11 97% 59.1
Rhode Island 8 97% 62.7
Minnesota 16 95% 57.4
Delaware 7 95% 60.6
Connecticut 22 95% 60.3
New Jersey 4 93% 57.4
Wisconsin 14 90% 55.6
Oregon 11 90% 64.0
New Mexico 6 90% 59.6
Virginia 42 87% 56.0
Colorado 10 86% 57.8
Michigan 8 85% 54.7
Pennsylvania 18 84% 56.9
Maine 16 83% 54.8
New Hampshire 11 80% 55.1
Ohio 9 75% 52.7
Hawaii 1 75% 69.9
Florida 21 75% 52.7
North Carolina 22 63% 51.9
Nevada 1 57% 51.2
Iowa 23 57% 52.8
Georgia 34 45% 48.6
Arizona 21 43% 48.4
Missouri 9 40% 48.9
Indiana 15 40% 48.6
Wyoming 2 30% 44.0
Kansas 11 30% 46.1
South Carolina 15 25% 45.2
North Dakota 3 25% 43.0
Utah 12 23% 43.6
Arkansas 15 20% 44.2
Alabama 6 18% 40.4
West Virginia 8 15% 37.8
Nebraska 10 15% 45.5
Montana 7 15% 47.7
Kentucky 7 15% 44.4
Texas 21 10% 44.0
Tennessee 11 10% 42.1
Mississippi 8 10% 44.1
Louisiana 12 8% 43.2
South Dakota 3 5% 42.2
Oklahoma 12 4% 31.7
Idaho 11 3% 34.5
Alaska 3 0% 43.4

8 thoughts on “Political scientists predict Clinton will win 347 electoral votes”

  1. Hi Andreas,

    Do you think that the fact that the PollyVote and the expert estimate error increased about 60 days before the election have something to do with the fact that the party conventions in 2004, 2008, and 2012 (with the exception of the 2004 DNC) were held at the end of August or beginning of September? Do you think that since the conventions have already past, this means that we are currently in the higher accuracy range, or since there is still over two months to the election mean that we still have to wait for the forecast to get more accurate? Thanks!

    1. Hi Ali,

      it could be that the higher error is due to the conventions. We haven’t looked at this in detail. Generally, the accuracy of polls and markets tends to improve closer to election day. Note, however, that even the maximum error (1.2 points) is quite small.

    1. The anomaly of the rise of the alt-right bucking the institutional Republicans & conservatives by and large doesn’t translate to the body politic as a whole within the general.

    2. I don’t see how any reasonable person can fault the experts for underestimating how stupid GOP voters are. That’s not what they do.

  2. LMFAO there is no honest press or polls anymore! People hate Hillary and Bill, only election fraud can pull this off for Hillary. This is a Trump hit piece that no one believes.

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