Jan

14

I have an interest in prediction markets (also known as information markets or idea futures), such as election betting odds, that allows people to place bets on who they think will be the next president. I wrote an article on my blog some time back (2020) describing the phenomena referred to as the "wisdom of the crowds" that makes these prediction markets possible:

For years now I have been fascinated by prediction markets. The source of excitement is the idea is that you can use financial markets to do inference — just like machine learning. A famous example of such prediction markets are the orange futures. The orange futures market is one that allows entities to buy oranges in advance. How it works, is that one can pay $1,000 to receive 1,000 oranges that will be delivered next year. An interesting side effect of this orange futures market is how it accurately predicts temperatures in certain locations more specifically, the temperature of the locations where the oranges are from.

Peter Ringel writes:

this is a clever thought, and also a terrible situation. I too noticed that it seems - in places - to be easier to predict pockets of the real economy with the financial markets. Of course, traders like it the other way around. Mkts got so efficient. The outside world has way more inefficiency left. (Also enjoyed your mention of "J" language - never heard about it before.) the source of excitement is the idea is that you can use financial markets to do inference.

Zubin Al Genubi comments:

The difference between prediction markets and financial markets is that prediction markets are binary outcomes and markets have non binary outcomes. The distributions are different.

Larry Williams responds:

What a great point. That’s a massive difference….then add in position size.

H. Humbert writes:

An option price seems awfully similar to a prediction market price: both deal with a discrete event at a particular time in the future (or at least close enough for most prediction markets), and right before expiration both, in a way, create a binary choice. I don't trade options, but that's what it appears like.

Zubin Al Genubi replies:

One big difference is options are subject to arbitrage. The prediction markets are not and get wildly inaccurate swings.

Big Al offers:

Binary Option
Superforecasting: The Art and Science of Prediction
Brier scores

From an interview with Michael Mauboussin:

…when you have an investment thesis to buy or sell something, that means you believe you're going to generate an excess return, or there's a mispricing in the market. And…that thesis should have sub-components to it that will allow us to create a scoring system. The most common of these or known of these is called a Brier Score….To have a Brier score you only need three things. You need an outcome that we can agree upon, within a time period that we are finite, with some probability….And so my argument is break down your thesis and put it into some Brier score ready predictions…what I find is the very discipline of writing those things down will force you or compel you to think more…deeply about them. For example, if you're assigning probabilities, you're going to immediately start searching for base rates.


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