Category: Experts

The PollyVote team has completed its 12th survey of elections experts to forecast the 2016 presidential election. In this survey, conducted between October 29 and 31, 13 academics from a variety of colleges and universities responded.

As in previous rounds, all respondents expect a Clinton win. However, her lead has narrowed substantially compared to the results of the previous survey conducted two weeks ago.

Whereas, in mid-October, the experts expected that Clinton will win the popular vote by more than nine points, the new average forecast is two percentage points lower, at 52.7% of the two-party vote (or about a 5.5-point margin). The individual forecasts ranged from 51.6% to 54.8%, with a standard deviation of only 0.8 points.

Polly thanks the experts who participated in this round, namely

1. Randall Adkins (University of Nebraska Omaha)
2. Lonna Rae Atkeson (University of New Mexico)
3. George Edwards (Texas A&M University)
4. Keith Gaddie (University of Oklahoma)
5. John Geer (Vanderbilt University)
6. Sandy Maisel (Colby College)
7. Michael Martinez (University of Florida)
8. Thomas Patterson (Harvard University)
9. Gerald Pomper (Rutgers University)
10. David Redlawsk (University of Delaware)
11. Larry Sabato (University of Virginia)
12. Michael Tesler (University of California, Irvine)
13. Charles Walcott (Virginia Tech)

The PollyVote team has conducted the third round of its state-level expert survey. According to the forecasts of 673 political scientists, Hillary Clinton will win 358 Electoral Votes, compared to 180 for Donald Trump.

This Electoral College prediction thus differs from the results of the first and second survey rounds,  when the experts’ aggregate forecast was that Clinton would gain 347 Electoral Votes, compared to 191 for Trump. The difference is due to Arizona (with its 11 Electoral Votes), which the experts now see leaning slightly towards the Democrats.

The following map visualizes the experts’ median estimates regarding Clinton’s chance of winning each state.

Nebraska and Maine deserve special attention, since these two states allocate two Electoral Votes to the popular vote winner plus one each to the popular vote winner in each Congressional district. The experts predict that all districts will go with the state-wide popular with two exceptions.

• In Nebraska’s 2nd district, the Democratic candidate is expected to win 50.8% of the two-party vote.
• In Maine’s 2nd district, the Republican candidate is expected to win the popular vote with a two-party vote share of 51.0%.

Method

We reached out to political scientists across the country and asked them 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?

For experts who regard Nebraska or Maine as their home state, we additionally asked them to predict the outcome in each congressional district.

The survey was conducted from October 15 to 19. A total of 673 experts made estimates as requested. The number of experts by state ranged from 2 to 39. The table below shows the number of respondents per state as well as the median answer for each question.

		Clinton’s predicted
State	N	Chance of winning	Two-party vote
District of Columbia	15	100%	93.8
Vermont	9	100%	67.4
Hawaii	2	100%	76.5
Maryland	26	100%	67.0
New Mexico	5	100%	59.0
Massachusetts	14	100%	67.6
New York	26	99%	65.2
California	23	99%	63.8
Rhode Island	5	99%	61.1
Washington	12	99%	60.3
Illinois	24	99%	59.7
Connecticut	21	99%	62.4
Oregon	9	95%	57.8
New Jersey	5	95%	63.2
Minnesota	18	95%	55.3
Michigan	12	91%	54.3
Delaware	11	90%	63.2
Wisconsin	14	90%	53.9
Virginia	39	90%	56.0
Pennsylvania	20	90%	54.3
Colorado	8	88%	54.9
Maine	14	84%	54.4
New Hampshire	14	80%	54.2
Nevada	5	75%	53.8
Florida	22	73%	51.6
North Carolina	24	65%	51.3
Ohio	12	58%	51.4
Iowa	19	52%	50.5
Arizona	16	50%	50.5
Missouri	11	45%	47.8
Utah	13	40%	47.6
Georgia	26	39%	48.4
Alaska	5	38%	45.8
South Carolina	14	25%	47.0
Indiana	15	20%	46.4
Texas	19	20%	46.7
Kansas	11	15%	46.0
Montana	5	15%	46.2
Kentucky	4	14%	41.5
Arkansas	12	11%	43.2
South Dakota	6	9%	40.3
North Dakota	6	7%	42.0
West Virginia	9	7%	37.6
Mississippi	14	7%	44.7
Alabama	5	5%	38.9
Louisiana	11	5%	40.9
Idaho	14	5%	37.8
Tennessee	8	4%	43.3
Nebraska	4	3%	42.2
Wyoming	4	1%	30.0
Oklahoma	13	0%	37.5

The PollyVote team has conducted the second round of its state-level expert survey. According to the experts’ judgment, Hillary Clinton will win 347 electoral votes, compared to 191 for Donald Trump.

This Electoral College forecast is similar to the previous survey’s results, although Clinton’s lead has considerably narrowed in a number of states, particularly Florida, North Carolina, Iowa, Ohio, and Nevada. That said, even if Clinton lost all five states, she would still end up with 273 electoral votes, three more than necessary to win the election.

The following map visualizes the experts’ median estimates regarding Clinton’s chance of winning each state.

In comparison, the latest PollyVote forecast, which also incorporates the results from the expert survey, predicts Clinton to gain 314 electoral votes, compared to 224 for Trump. This difference results from different forecasts for Ohio and North Carolina. While the experts predict Clinton to prevail in these states, the combined PollyVote forecasts currently favors Trump.

Method

We reached out to political scientists across the country and asked them 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?

The survey was conducted from September 19 to 22. A total of 653 experts made estimates as requested. The number of experts by state ranged from 2 to 35. The table at the end of this post shows the number of respondents per state as well as the median answer for each question.

		Clinton’s predicted
State	N	Chance of winning	Two-party vote
District of Columbia	13	100%	94.6
Vermont	9	100%	66.7
Hawaii	2	100%	69.9
New York	25	99%	64.2
Massachusetts	20	99%	66.7
Maryland	26	99%	63.6
California	23	99%	62.2
Rhode Island	8	97%	62.7
Washington	11	96%	59.1
Illinois	25	95%	60.4
Delaware	11	95%	60.6
Connecticut	21	95%	60.3
Oregon	11	93%	64.0
New Jersey	5	90%	57.4
New Mexico	4	87%	59.6
Minnesota	17	85%	57.4
Colorado	9	80%	57.8
Wisconsin	14	78%	55.6
Virginia	35	75%	56.0
Pennsylvania	15	75%	56.9
Maine	12	75%	54.8
Michigan	14	70%	54.7
New Hampshire	16	64%	55.1
Florida	16	54%	52.7
North Carolina	22	54%	51.9
Nevada	5	52%	51.2
Ohio	9	51%	52.7
Iowa	15	51%	52.8
Alaska	3	45%	43.4
Arizona	19	40%	48.4
Missouri	11	40%	48.9
Georgia	20	35%	48.6
Arkansas	10	30%	44.2
Indiana	14	18%	48.6
Kansas	8	13%	46.1
Texas	24	13%	44.0
South Carolina	13	10%	45.2
North Dakota	5	10%	43.0
Utah	18	10%	43.6
Kentucky	4	10%	44.4
Wyoming	5	8%	44.0
Alabama	7	5%	40.4
West Virginia	8	5%	37.8
Montana	5	5%	47.7
Mississippi	15	5%	44.1
Louisiana	12	5%	43.2
Tennessee	12	3%	42.1
South Dakota	4	3%	42.2
Nebraska	3	2%	45.5
Idaho	11	1%	34.5
Oklahoma	9	1%	31.7

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