How Accurate Were the Political Science Forecasts of the 2016 Presidential Election?

by James E. Campbell, Guest Columnist
Sabato’s Crystal Ball, University of Virginia Center for Politics

With the dust settling from one of the most brutal and nasty presidential campaigns in modern American history and with the late vote returns creeping up to a final count, it is time to take stock of the presidential election forecasts offered initially to readers of the Crystal Ball website and then published in the October issue of PS: Political Science and Politics. Despite the surprising electoral vote victory of Donald Trump, the vote count as of one week after the election indicates that Democratic nominee Hillary Clinton received 50.5% of the two-party popular vote cast nationwide to Republican President-elect (yes, it is still jolting) Trump’s 49.5%.

So how did the forecasts do? From late June to early September in Sabato’s Crystal Ball, eight forecasters or teams of forecasters issued 10 presidential election forecasts of the national two-party popular vote (along with the PollyVote meta-forecast assembled from array of different types of forecasts). Aside from a few minor updates, these were the same forecasts later published in PS (in no case did the difference between the Crystal Ball and PS reported forecast differ by more than two-tenths of a percentage point). Table 1 reports the forecasts from the closest to the actual vote division as it appears at this time to the forecast with the largest absolute error.

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Table 1: Political science forecasts of the 2016 presidential election

Read the full analysis.