The Wages of Election Modeling: 538 vs. DDHQ
Putting forecasters to the test by simulating the gains (or losses) you'd make trading their recommendations on Polymarket every day
This is our 2nd forecaster match-up. See the original post in the series for more context on what’s going on here and the results of Nate Silver vs. Lichtman’s 13 Keys.
The Rules
Forecasters start with $10,000.
Once a day, the forecasters get to buy or sell/short Trump shares, depending on whether their own odds are higher or lower than the Polymarket price.
The size of each trade is driven by the size of their bankroll and how certain they are of the mispricing - the bigger the mismatch, the bigger the trade.
We mark the holdings to market each day, so unrealized gains are reflected in daily account value.
A total of 48 trades are made, from September 19 through November 5. Any realized gains booked along the way are theirs too keep. After the election, all Trump shares pay $1 and Harris shares become worthless.
ABC News’ 538 vs. Decision Desk HQ
TL;DR Another double atrocity. DDHQ “wins” by losing a little less than 538. 538 came close to saving itself a few bucks in the final days, until it herded back to a last-minute Harris win. DDHQ managed to finish with Trump favored, but remained so far under the Polymarket price that it always guided toward buying Harris on all but one day (when it made no trade). Still, DDHQ’s somewhat shallower bath makes them our best performer to date!
Below, we dive into the daily performance metrics - how the respective forecasters’ odds differed from market prices each day, how big a daily bet they place on Trump or Harris as a result, and how their portfolio value grew/shrank over time.
Let us know if there’s a particular head-to-head you’d like to see. Surely at least a few (one?) will turn a profit…
Previously…
