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Track Record - Election Betting Odds

By Maxim Lott

Updated Nov 13, 2018

ElectionBettingOdds.com tracked some 462 different candidate chances across dozens of races and states in 2016 and 2018.

How accurate has this site been?

When a candidate favored by bettors loses, it's easy to fall into the trap of thinking the bettors were "wrong". But remember that when bettors give someone, for example, a 65% chance to win -- that also means the bettors give the person a 35% chance to lose.

The following graph shows how closely the betting tracked reality.

The blue line shows what predictions would look like if they were perfect. Where the red line differs from the blue line, the predictions were off somewhat:

The graph below holds predictions to a more precise standard -- 10% intervals, with smaller sample sizes.

The biggest inaccuracy came in 12 races where bettors put the odds at between 40% and 50%. In those cases, candidates actually won 58% of the time -- 7 of those races were won, while 5 were lost. The exact reverse happened for the 50-60% bracket.

This is a small sample size, however, and it is likely that, as more elections are tracked, this line will begin to match the first graph on the page.

Looking at betting beats listening only to polls, according to several studies, such as this one in Public Opinion Quarterly. Also, a study by the author of Superforecasting got smart people to make predictions for study of their accuracy:

I managed to recruit 284 serious professionals, cardcarrying experts whose livelihoods involved analyzing political and economic trends and events... Almost all had postgraduate training; half had PhDs...

In the end:

the average expert was roughly as accurate as a dart-throwing chimpanzee.

Certain groups of pundits - namely ideological ones and those with frequent TV appearances - actually did worse than dart-throwing chimpanzees.

This post has been updated with the 2018 elections. To see the old graph with only 2016 data, see here. In that analysis, the fine-grained graph looked more accurate than after the 2018 election.

To come: an analysis looking at more predictions made by the site over time (every day, or even every 5 minutes) -- as opposed to data used in the above graph, which just looks at a single prediction for each candidate, taken on the morning of the election.

As an aside, here were the biggest upsets we've tracked. The following candidates were big underdogs in the betting. All won:

Below is ElectionBettingOdds.com's full track record for 2016 (send any questions or comments to Maxim Lott at maxim.lott@gmail.com or at @maximlott on Twitter.) The graph above is based on these data:

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