Nov 6

Market inspired by a comment from @MarcusAbramovitch

I will assess a variety of markets pertaining to the 2024 election, depending on which markets are created and have enough users betting on them. Markets that will likely be included (provided I can find real-money markets on these questions):

-Presidential primary markets for Reps and Dems

-Presidential general election market

-Who will win the house

-Who will win the senate

-Who will win particular swing states in the presidential election

-Who will win key senate/house races

-Will the final margin of the election be within a certain range

Any other large markets concerning the election that I can find on both real-money markets and Manifold may also be included. I will likely try to use Polymarket markets, but due to the changing regulatory landscape of real-money markets, I'm hesitant to commit to one real-money prediction site or another. If there are multiple large sites running markets, we can select the one with the largest amount of money / users.

I will select multiple time horizons for each question: for the primary markets, obviously longer time horizons will be needed, as they will converge over the course of the primaries. For most of the other questions, I will likely evaluate at, say, 1 day before, 1 month before, several months before.

I will then generate an R^2 or logloss score for the predictions from Manifold and the real-money markets and compare them. This will be scored like a prediction contest (which I have some experience administering).

If it is clear that Manifold did better than real-money markets, I will resolve YES.

If it is clear that Manifold did worse than real-money markets, I will resolve NO.

If it is truly too close to call (statistical metrics are really trivially different, or different metrics clearly diverge and the final answer is sensitive to small statistical evaluation choices) I will resolve to 50%!

If Manifold or real-money markets for some reason change to not be able to address political questions, or world events lead to a cancellation or restructuring of the 2024 election, or some other crazy stuff prevents this question from being answered, I will resolve N/A.

I will not bet on this market as I think the criteria is subjective. I initially thought that Manifold would be likely to beat real-money markets, but I thought about it more and I'm not so confident, and I'm genuinely interested in learning the answer to this question and will attempt to be as impartial as possible. I will consult with other manifold users on how best to assess and evaluate this question, and will be transparent with how I'm collecting and evaluating the data.

I reserve the right to tweak the description and methodology, especially in the next couple months before any actual data points are revealed, to be receptive of user feedback on the question.

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bought Ṁ20 of NO

I think Polymarket will beat Manifold this time because Manifold has Trump still lower than he should be.

FYI link to 2022 election analysis (Manifold was more accurate!)


Will Manifold beat PredictIt on midterms predictions?
Resolved YES. I will score several prediction platforms on a set of 10 questions on the outcome of the 2022 US midterm elections. For each prediction platform, I will take the predicted probabilities on Monday evening, and compute the average log score (a measure of the prediction's accuracy) on these questions. This question will resolve as per the title question. "Beat" will be defined as having a better (higher) log score. The question will resolve after all the relevant races are called. The questions and scoring methodology are described here: https://manifold.markets/post/comparing-election-forecast-accurac See related questions here: https://manifold.markets/group/election-forecast-comparison Note that the election results are highly correlated, so the platform that turns out to be most accurate may not have actually been the best set of predictions. The forecast that scores best is probably going to be the forecast that happened to best predict the broader question of how left or right skewed the entire election was, but some of that might be "luck" which it might not be able to repeat across many different election years. To truly measure accuracy well, we'd need to run this experiment several times over different election cycles. I've selected this set of 10 questions: Senate control House control Senate races Pennsylvania - Mehmet Oz R vs John Fetterman D Nevada - Catherine Cortez Masto R vs Adam Laxalt D Georgia - Herschel Walker R vs Raphael Warnock D Wisconsin - Ron Johnson R vs Mandela Barnes D Ohio - J. D. Vance R vs Tim Ryan D Arizona - Blake Masters R vs Mark Kelly D Governor races Texas - Greg Abbott R vs Beto O'Rourke D Pennsylvania - Doug Mastriano R vs Josh Shapiro D Close date updated to 2022-12-15 11:59 am
bought Ṁ100 of NO

I think this question will largely be a coin flip on whether the election overall goes more left or more right, because different platforms tend to have different left-right biases. See my analysis at https://firstsigma.substack.com/p/midterm-elections-forecast-comparison-analysis

@jack Yep I understand the limitations completely. I’m hoping to be able to include a broader range of questions about the election that are ideally less correlated (perhaps meta-questions about turnout, demographic swings, etc) but that relies on polymarket having those questions available which I can’t control. I also hope that including multiple time horizons for each question will improve this as well.

@jack I’m definitely open to any methodology suggestions you have since you’ve done this before!

predicts NO

@BenjaminShindel Sure! I think what you wrote in the description is great. Just like you mentioned, one of the biggest limitations in my analysis was finding equivalent forecasts between different platforms. I ended up with a selection of about a dozen markets that were on all the big forecasting platforms - basically the ones you listed except for margin of victory. Would love to look at a broader range of questions if they exist on multiple platforms. More time horizons is great too.

Another thing to be aware of is that the definition of price gets complicated. On manifold it's just one number, but on Polymarket you have a bid-ask spread (the avg of the two is how they define the price) and on PredictIt not only do you have a bid-ask spread but you also have separately priced YES and NO shares.

bought Ṁ100 of NO

Glad you made this!

Thanks for the subsidies @firstuserhere and @SG !

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