Which is a more reliable predictor of election outcomes: polls or betting markets?

[DrPepper12]

Polls

Betting markets

[msc545]

Prediction/Betting Markets

These markets (e. g., the Iowa Electronic Markets, or more recently crypto/online markets) essentially aggregate the “wisdom of the crowd” by having people put real money on outcomes. That financial stake can help discipline predictions.

Some studies show that, historically, prediction markets have had somewhat lower error than standard polls. For example, one survey found that between 1988-2004 the Iowa markets beat 74 % of the polls.

More recent work (e. g., analyzing the 2024 U. S. presidential election market on Polymarket) finds that markets may have been more decisive and earlier-than-polls in signalling a winner in certain swing states

But the markets are not flawless: issues of liquidity, manipulation, representativeness of the bettors, and the size of the market all limit certainty.

Polls ask people directly for their voting intention (or sometimes their expectation of the outcome). They offer broad samples of intended behaviour.
Some research (for example, by Justin Wolfers & David Rothschild) shows that asking survey respondents “who do you think will win?” (expectations) can sometimes outperform asking “who will you vote for?” (intentions). Brookings
Polls have well-documented errors (non-response bias, late shifts in opinion, turnout uncertainty, state-level variation) which have become more pronounced in recent elections.

🎯 Which is “more reliable”?

There isn’t a clear winner in all cases—but here are some guiding observations:

If you’re looking early in the campaign, prediction markets may give earlier signals because bettors may respond to emerging information more fluidly than polls. For instance, the 2021 study found markets performed better several months out, with models/polls catching up closer to the election.

As you get closer to election day, polls still matter, especially state-level polling (in systems like the U. S. Electoral College). Some studies show that once you control for “trial-heat” polls (last-week polls of voter intention) the extra value of market data shrinks.

The best accuracy often comes from combining both markets and polls (and possibly other indicators like economic data, models, etc.). For example, one study found that averaging market and model forecasts did better than either alone. arXiv+1
Because both polls and markets have blind-spots (polls: sampling/turnout; markets: representativeness/liquidity/manipulation), relying on only one is riskier.

Use polls for detailed “what voters are saying now/will do” insight — especially if you can access high-quality state-level surveying.

Use prediction/betting markets to gauge “what people expect will happen (and are willing to put money on).”

When both align (e. g., polls indicate Candidate A leads + markets heavily favour A), your confidence should be higher.

When they diverge, it signals higher uncertainty or that one of the sources may have a bias or missing piece of information.

Be cautious about interpretation: neither gives guaranteed outcomes, just probabilities and signals.

[DrPepper12]

Agreed

[msc545]

Thanks for mho.

[exitseven]

I say betting markets. People put their money where the mouths are.

[DrPepper12]

BINGO!

[exitseven]

Thanks for the MHO😎

[Anonymous]

Neither can be trusted as they are influenced often to give a desired result.

[lightbulb27]

good Q, don't know.

[Likes2drive]

Polls usually

[RedInnocent69]

Polls, it’s just how you read them