Neither prediction markets nor polls are reliably more accurate; they’re good at different things. Polling averages measure what voters say right now and have a long, documented error record. Markets turn polls plus everything else traders know into a probability, react to news within minutes, and have both beaten and badly trailed the polls in recent elections. The best read usually comes from checking one against the other.
Why is comparing them tricky? #
A poll and a market answer different questions, so “accuracy” means something different for each.
- A poll estimates vote share: Candidate A 48%, Candidate B 45%. You judge it by how close that share lands to the result.
- A market estimates the probability of winning: Candidate A at 70ยข means about a 70% chance. You can’t grade a single probability by whether the favorite won. A 70% favorite should lose 3 times in 10.
So to compare fairly you either convert polls into win probabilities (which is what forecast models do) or you score markets over many races, using measures like the Brier score that reward confident correct calls and punish confident wrong ones. How to read political betting odds covers converting prices into probabilities.
What does the research say? #
Academic work points both ways.
- Long-running studies of the Iowa Electronic Markets, a small academic market run by the University of Iowa since 1988, found its prices were usually closer to final presidential vote shares than individual polls taken at the same time, especially months before the election.
- Other political scientists, notably Robert Erikson and Christopher Wlezien, showed that once polls are adjusted for how leads typically shrink as Election Day approaches, poll-based forecasts do as well as or better than markets.
The fair summary: markets tend to beat a raw single poll. They don’t consistently beat a well-built polling average or forecast model.
How did markets and polls do in recent elections? #
| Election | Polls and averages | Markets | What happened |
|---|---|---|---|
| 2016 presidential | Clinton led national and most swing-state averages | Clinton a clear favorite, roughly in line with poll-based models | Trump won; both missed, polls underestimated him in the Upper Midwest |
| 2020 presidential | Biden led by large margins in averages | Biden favored, but with less confidence than most models | Biden won narrowly; polls overstated his margin; markets’ caution looked wise |
| 2022 midterms | High-quality averages showed close Senate races | Traders leaned hard toward a Republican Senate and a large House wave | Democrats held the Senate; Republicans won the House narrowly; averages did better |
| 2024 presidential | Averages near a tie nationally and in swing states | Trump favored in the final weeks | Trump won all seven swing states; polls underestimated him by a few points |
Two lessons stand out. First, when polls share a systematic error (2016, 2020, 2024 all ran toward Democrats), markets that lean on polls inherit some of it. Second, markets can ride a narrative. In 2022 a flood of partisan-sponsored polls and a “red wave” story pushed prices well past what the nonpartisan averages supported, and the averages were closer.
What are polls better at? #
- Asking voters directly. A good poll is a sample of the people who will decide the race. A market is a sample of traders.
- Explaining why. Polls tell you how groups are moving: by age, education, region, party. A price can’t.
- Transparency. Pollsters publish sample sizes, dates and methods, so you can judge them. You rarely know who is behind a price move.
- Low-attention races. In a governor’s race with little trading, a couple of quality polls may carry more information than a thin market.
Their weaknesses are real: response rates in the low single digits, turnout models that can miss, and the lag of fielding and publishing, which means a poll can’t reflect news from yesterday. See polling herding for one way averages can look more certain than they are.
What are markets better at? #
- Speed. Prices move within minutes of a debate moment, a withdrawal or a court ruling. Polls take days.
- Folding in non-poll information. State partisanship, candidate quality, fundraising, expected polling error and legal fights all get priced in.
- Expressing probability. A market directly answers “who is likely to win?”, which is what many people actually want to know.
Their weaknesses: traders skew young, male and online; small markets can be moved by a few large orders (can prediction markets be manipulated?); long shots tend to be overpriced; and a strong narrative can override the data.
How to use both for the 2026 midterms #
- Start with polling averages. For Senate and governor races, a 30-day average of recent polls is your baseline. For the House, use the generic congressional ballot.
- Check the market for the same race. Convert the price to a probability.
- Look for disagreement. If a Senate race is tied in the polls but the market has one side at 70%, ask why. Maybe the state’s partisan lean, maybe an expected polling error, maybe just a thin market.
- Discount thin markets. Chamber-control markets carry far more money than single-state primaries. Trust heavily traded prices more.
- Watch direction more than level. A market and a polling average moving the same way over two weeks is a stronger signal than either alone.
Election Tracker, our free iPhone app, is set up for exactly this comparison. Its polling tabs group Senate, governor and generic-ballot polls by race, each with a 30-day average and every poll’s pollster, sample size, population and dates. Its Market Sentiment tab shows read-only Polymarket prices for markets such as Senate and House control, with 24-hour moves, under a disclaimer that prices are sentiment, not forecasts. You can check a race’s polling and its market price in two taps and see whether they agree.
Frequently asked questions #
Do prediction markets react faster than polls? #
Yes. Prices can move within minutes of news, while a quality poll takes several days to field, weight and publish. Speed isn’t the same as accuracy, though: early market reactions sometimes overshoot and reverse.
Were the prediction markets right about 2024? #
Markets favored Trump in the final weeks, and he won, while polling averages showed a close race. That’s one election. In 2022 the same kind of confidence pointed the wrong way on the Senate, so one good call doesn’t settle the question.
Why do markets and polls sometimes disagree? #
They measure different things. Polls report current vote intention; markets price the chance of winning, factoring in state lean, candidate quality, expected polling error and news that hasn’t reached the polls yet. Disagreements are worth investigating, not automatically resolving in favor of either.
Can I trust a single poll over a market? #
Rarely. A single poll carries a margin of error of several points, so a market that reflects many polls plus other information will usually be a better guide. A polling average is the fairer comparison.