Predyx BuddyPredyx Buddy
This was just a little side project to help people make smarter bets on Predyx.
Enter your beliefs on what the correct probabilities should be, and the tool will tell you the optimal betting strategy. There's also a slider for how conservative you want to be. I predict there to be some fairly good opportunities for strategic bets, especially in multi-outcome markets where the optimal strategy is harder to think through.
Consider this a Christmas gift to all stackers! But if you benefit from this tool, I'd appreciate any thanks in the form of sats, as well as feedback for improving the tool.
Hope this helps! Happy predicting!
The Math Behind PredyxThe Math Behind Predyx
Predyx uses a "logarithmic market scoring rule", basically, a pricing algorithm. When you buy or sell shares on Predyx, you are not buying or selling shares from another market participant, you are buying and selling shares from the platform. Here is the explanation in their own words, with a focus on helping market creators. My tool is meant to help market participants, not creators.
Let there be outcomes, and let be the current number of outstanding shares for outcome .
The LMSR rule says that the current probability (and therefore share price) of outcome is:
where is the "market liquidity" parameter, something set up by the market creator which influences how much sats are available in the market to earn. (Higher liquidity means the market is harder to shift but there's more potential earnings for each trade; lower liquidity means the market is easy to shift but there's less potential earnings for each trade.)
Note that the market creator also "seeds" the market with a number of initial phantom shares that you won't see in the order history, but serve to set the initial probabilities of the market.
The nice thing about this formula is that there is an easy rule to tell you how many shares of each outcome to purchase/sell in order to shift the probabilities towards what you think are more accurate:
Optimal betting strategyOptimal betting strategy
Let indicate the current market probabilities, and let be your target probabilities (the probabilities that you believe more accurately reflect reality). Choose one outcome to hold fixed (that is, to not buy or sell any shares). For simplicity, let's call that outcome 1. Then, for every other share, the optimal rule for buying is:
If you believe that outcome is more likely than the current probabilities indicate, you'll buy more of outcome . If you believe that outcome is less likely than current probabilities, you'll sell more of outcome .
The strategy can also be adjusted so that it can be implemented with only buys. You simply add a constant to all until none of them are negative (sales) and all of them are positive (buys). Since shifting all shares by a constant amount doesn't change the target probabilities, this results in the same expected profit from the trade.
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Are you suggesting wild ass guessing is not the optimal betting strategy?
Now you can wild-ass guess more sophisticatedly
I am so smart. SMRT.
Yikes!! My gut feelings are getting destroyed by maths!
Nice piece of work!
Wish to see Predyx updating their pricing algorithm one day, or at least allow for API calls (so your tool could run the strategy) or a least! limit orders.
I know all will come one day, fingers crossed!
Very cool!
I've recommended they implement something like this for a new mechanism that allows participants to directly input the probabilities they want and Predyx tells them the cheapest way (including sales) to get there.
It doesn't look like fees are taken into account in your tool (maybe they don't matter for what you're trying to do). Something that might be helpful would be a tool that gives the best ROI, based on beliefs and fee structure.
I thought about including the fees, but I felt that would be too many input parameters to adjust, making the tool more unwieldly. It's easy enough for users to check the fees on their own and subtract them out from the cost and expected payout.
I don't know of Predyx has an API, but a cool thing would be if the user could simply enter the URL of the market and have all the parameters auto-filled. @mega_dreamer @Team_Predyx
So cool!
I think Predyx uses more sophisticated formula, I mean maybe some adition to the formula. It's not that you can always win or there's always some arbitrage on a market. I'm not sure though. My maths is too weak to understand formulas a lot.
I'll still try this tool and see if it works.
The optimal bet is only optimal if you have the correct beliefs, which you likely don't, so there isn't really an arbitrage opportunity here. The "expected profit" could be wrong if your beliefs are wrong.
Afaict, my math is the same as theirs. But I simplified the presentation a bit (with my discussion of phantom shares which abstracts from the a parameters)
What I particularly like is the flexibility you built in with the conservative slider. In the real world traders are often not fully confident in their estimates and allowing them to scale their risk down without changing the direction of their conviction is critical for long term survivability.
If people take the time to understand how this works they can spot edges especially in multi outcome markets where current prices often over or under value certain events. Over time these small edges compound and that is how disciplined market participants end up consistently profitable while casual bettors wonder why they cannot beat the odds...