First PollyVote forecast predicts a tight race

The first PollyVote forecast for the 2020 U.S. presidential election, published in late April, predicts a tight race for the national popular vote.

As of April 26, the combined PollyVote predicts incumbent President Donald Trump to gain 49.1% of the popular two-party vote, compared to 50.9% for former Vice President Joe Biden, with an 80%-uncertainty interval of +/-2.7 percentage points.

Based on these numbers, the estimated probability for Biden to win the popular vote is 67%. In other words, the PollyVote predicts Biden to win the popular vote two out of three times, whereas Trump is predicted to win one out of three times.

Table 1 shows the point forecasts from the PollyVote and the components, for which data are currently available. Forecasts based on both polls (intentions) and expectations see Biden ahead, whereas model-based forecasts and naive forecasts see a very small advantage for Trump.

MethodTrumpBiden
PollyVote49.150.9
Intentions (polls) (RCP average)46.753.3
Expectations48.451.6
– Prediction markets (7-day IEM average)49.051.0
Expert judgment47.752.3
Models50.849.2
– Retrospective (1 model, DeSart)54.445.6
– Hybrid (1 model, Fair)47.152.9
Naive forecast (2 models, electoral cycle and 50/50)50.649.4
Table 1: The PollyVote and its components, forecasts from April 26, 2020

It should be noted that available data that go into the PollyVote are still limited. The poll-based component is merely based on the RCP average, prediction markets rely on the small-scale Iowa Electronic Markets, and there is only one model forecast each in the retrospective model and the hybrid model category.

Loyal followers of the PollyVote will note that the PollyVote structure has changed compared to previous elections. We will explain our rationale for this adjustment in a future post. Stay tuned.

Final PollyVote forecast: Clinton will win

All numbers are in and, according to the PollyVote, Hillary Clinton will become the first female president of the United States.

Popular and Electoral Vote Prediction

Clinton will win the popular vote by 5.0 percentage points in the two-party vote (52.5% vs. 47.5%). Based on the PollyVote’s historical error, Clinton’s chance to win the popular vote is above 99%. In terms of the Electoral College, Polly predicts Clinton to receive 323 electoral votes compared to 215 for Trump.

Forecast over the course of the campaign

Forecasting is useful only when it can aid decision-making. Thus, Election Eve forecasts are only for entertainment and betting— and writing victory and concession speeches.

The PollyVote has predicted Clinton to win beginning with its first release in early January 2016. Since the first Super Tuesday on March 1st, when it became clear that Trump would become the Republican nominee, Clinton’s lead in the PollyVote forecast averaged 5.6 points. Throughout the course of the campaign, it ranged from a minimum of 3.8 points to a maximum of 8.2 points. In other words, the PollyVote never had Trump close to winning.

Since its launch in 2004, the PollyVote has always correctly predicted the winner on any given day, months in advance, and with little forecast error. Tonight, we will find out whether Polly the Parrot will keep her clean slate. Check back in the days to come as we will provide analyses of the different forecasting methods’ accuracy.

Democrats gain after NH primary

The results of the New Hampshire primary might look good for Donald Trump’s prospects to win the Republican nomination. And yet, according to the PollyVote, the Democratic party is the real winner of yesterday’s election. As a result of Trump taking back the lead in the PredictWise GOP nomination forecast, PollyVote’s forecast of the Democratic two-party vote share in the general election has increased by 1.2 percentage points to currently 51.5% (vs. 48.5% for the Republicans). This is the largest lead for the Democrats since PollyVote published its first forecast on January 1st, 2016.

First PollyVote forecast predicts close race

Today, the PollyVote published its first forecast for the 2016 election. Her first forecast of the national popular two-party vote predicts a virtual tie, with the Democrats at 50.1%, and the Republicans at 49.9% of the vote.

The PollyVote first started in 2004 by political scientists and forecasting experts and has accurately forecast US presidential elections since then. For details about the procedure as well as historical data, see the published research or read the FAQ.

We will have some exciting additions to the PollyVote in 2016. Stay tuned!