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kwar13yesterday at 5:26 PM6 repliesview on HN

This article lacks even the most basic understanding of probability and statistics. Slot machines "93 cents on the dollar" return is a statistical certainty of 7% loss. You are playing a repeated game which by the law of large numbers will converge to the 93% probability.

In prediction markets if the markets are fully efficiently priced, in the absence of transaction costs you WILL get 100% back in the long run.

Slots are also unskilled games, prediction markets clearly some participants have a clear market edge, thus not efficiently priced.


Replies

jjmarryesterday at 6:08 PM

If you read the article:

> Takers pay a structural premium for affirmative "YES" outcomes while Makers capture an "Optimism Tax" simply by selling into this biased flow.

It's still operating like a casino in that there's a "house edge" that comes from taking bets. Unlike a casino, there is nothing stopping the average person from market making, which is why it doesn't make sense this structural inequality exists.

jonbeckeryesterday at 6:26 PM

i understand how probability works. the "93 cents" vs "43 cents" comparison is looking at realized historical data, not theoretical odds. if the markets were efficiently priced, you would get 100% back. the entire point of the paper is showing that, historically, they aren't efficiently priced (longshots return ~43%), and explaining who captures that inefficiency.

pjc50yesterday at 5:46 PM

So clearly the market isn't efficiently priced.

kibwenyesterday at 5:40 PM

> In prediction markets if the markets are fully efficiently priced, in the absence of transaction costs you WILL get 100% back in the long run.

This is basically equivalent to the observation that, in a perfectly efficient market, no entity can ever make a profit.

And yet, in the real world, entities make profits all the time. In fact, they make wild, unimaginable, world-changing, history-altering profits. This is a tacit admission that our markets aren't even remotely efficient, and that includes predictions markets. Efficient, rational markets are the exception, not the rule.

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chinathrowyesterday at 5:55 PM

Do you work for a prediction market or do you participate in one?