PredictWise Relaunch

Since the 2016 election, we at PredictWise have worked on a serious relaunch of PredictWise 2.0, also known as the PredictWise Public Opinion Engine – in stealth, reflecting the new political reality we face today. Here is the short of it:

Our engine turns state-of-the-art behavioral data + polling + analytics into uniquely fast, accurate, [...] Continue Reading

General Questions
What is PredictWise?
PredictWise is a website for a project that studies the collection of individual-level data for predictions and public opinion, aggregation of that data, and usage. PredictWise focuses on public domains, such as: politics, sports, finance, and entertainment. What you see is the continuously running market data and blog posts that show a snapshot of public opinion. What you do not see is the research aspect of the work that is housed @ and (coming soon), more continuously updated public opinion data.
What is the point of PredictWise?
There were two goals of this project from its inception: (1) Displaying the fruit of research in real-time to ensured more comprehensive data collection and no look-ahead bias in the methodology. (2) We thought it would be interesting and informative for people to better understand the world. And, hopefully make more informed decisions with that.
What is the point of PredictWise's data collection?
While the main focus of the site is aggregating data that is already available: markets, polling, etc., we increasing run our own data collection. Found data is great, but it has its limits. Our own data provides more depth and answers questions more directly than found data.
Who runs PredictWise?
David Rothschild and Tobi Konitzer run PredictWise on a daily basis. If you are interested in blogging or helping in any other way, please email us @ [email protected]
Should I make any bets based on this information?
No, betting money on sports, politics, or anything else is a bad idea. Not only is it losing proposition due to the house's commission, but it is addictive, destructive, and - depending on your location - most likely illegal.
David Rothschild
Who is David Rothschild?
David Rothschild is an economist at Microsoft Research. He started PredictWise, along with his friend Andrew Leonard, as a graduate student at University of Pennsylvania's Wharton School. The site is designed to showcase the fun, public aspects of his academic research. You can learn more about his research @
How to I contact David Rothschild?
By email: [email protected]
Tobi Konitzer
Who is Tobi Konitzer?
Konitzer has a Ph.D in communication from Stanford University. He has researched and written extensively, in both the academic and popular press, on public opinion polling and Big Data, algorithms and politics. Before joining PredictWise, Konitzer worked on non-representative polling for Facebook Research.
How to I contact Tobi Konitzer?
By email: [email protected]
PredictWise Data
What is PredictWise Polling Data?
We are actively collecting about 20,000 responses per month on a variety of questions. We are then modeling and post-stratifying the data to likely voting populations. We are reporting these findings in blog posts.
Prediction Market Data
What is Market Data?
Market data is prices available from publicly facing markets that sell contracts we find interesting. We are translating the prices for you and updating them in real-time.
How we cleaning Market Data
Generically, most tables focus on market data. There is a three step process. Step 1: construct prices from the back/sell, lay/bid, and last transaction odd/price in the order book. We always take the average of the highest price traders are willing to buy a marginal share and the lowest price people are willing to sell a marginal share, unless the differential is too large or does not exist. Step 2: correct for historical bias and increased uncertainty in constructed prices near $0 or $1. We raise all of the constructed prices to a pre-set value depending on the domain. Step 3: normalized to equal 100% for any mutually exclusive set of outcomes.
Data Sources: Markets
What is Betfair?
Betfair, based in the United Kingdom, is the world's largest internet betting exchange. Rather than having a bookmaker create odds, the odds for every bet are determined by the market of bettors, working similarly to a stock market. Bettors can either "Back" (buy) or "Lay" (sell) a given bet at certain odds, and the odds move as Backs and Lays are matched. Betfair is legal in the UK and other countries, but it is illegal to bet money on Betfair as a resident of the United States.
What are the Iowa Electronic Markets (IEM)?
The Iowa Electronic Markets (IEM) are a group of real-money prediction markets operated by the University of Iowa Tippie College of Business. The IEM is not-for-profit; the markets are run for educational and research purposes. Because of the small sums wagered and the academic focus, the IEM has received no-action relief from the United States government, meaning U.S.-based speculators can legally risk between $5 and $500 on a wager.
What is PredictIt?
PredicIt is an exchange that operates legal prediction markets for United States citizens. PredictIt has received a no-action relief from the United States government, meaning U.S.-based speculators can legally risk up to $850 in a market.
What is Hypermind?
Hypermind is a play money-market, but has real prizes that correspond to the play-money. Rather than focus on large quantities of users, it tries to use highly trained collections of traders.
What is the Hollywood Stock Exchange (HSX)?
The Hollywood Stock Exchange (HSX) is a play-money prediction market in which users can buy or sell shares in movies, actors, directors, and other Hollywood-related topics. For example, users can buy or sell shares of an upcoming film as a means predicting how well that film will do at the box office in its first four weekends of wide release, and then be ranked based on the accuracy of their predictions. Because HSX involves only simulated money, it is legal for all participants.
What is Oddschecker?
Oddschecker is a site that posts the latest bookie odds/prices to sell contracts for upcoming events. We generally focus on the highest lowest odds/prices that any of the bookies will sell at, as the marginal sell price from bookies.
Technical Questions
Sometimes PredictWise only lists one source but has a slightly different prediction than that source - why is that?
The answer is de-biasing and normalizing. First, we are adjusting for known biases between raw data and outcomes. Second, when the list of possible outcomes is finite (such as the 32 teams that can win the Super Bowl), the sum of every possible outcome's probability should equal 100%. Because our sources must create a separate market for each outcome, this is not always the case. To adjust for this, we divide each outcome's probability by the sum of every outcome's probability and use that as our prediction. We always try to show the raw data for sophisticated users who do not just want to see the polished prediction.
You list a single price from prediction markets like Betfair, but in actuality prediction markets have simultaneous (and different) Bid price, Ask price, and Last price. How do you calculate this?
As long as the spread between the Bid and Ask prices is less than 15 points, we take the average of the two. If not the spread is larger, we may go to the last price. Again, we always try to show the raw data for sophisticated users who do not just want to see the polished prices and predictions.
What happens when a market lacks liquidity and there is a bid, but no ask or an ask, but no bid?
If there is a bid/back that is greater than 50 and no ask/lay, we take the average of the bid/back and 100. If there is an ask/lay that is less than 50 and no bid/back, we take the average of the ask/lay and 0. If neither of those conditions hold, we take the last price. We understand that sometimes this does not yield the obvious answer, but we need the numbers to speak for themselves, so we never adjust any numbers manually. Again, we always try to show the raw data for sophisticated users who do not just want to see the polished prices and predictions.