15. At the end of 2023, will prediction markets say Joe Biden is the most likely Democratic nominee for President in 2024?
resolved Jan 1

We will use Polymarket to resolve these questions looking at 00:01 Jan 1st 2024. If Polymarket stops existing or by our judgment is no longer credible, we will use whichever Manifold market on the question has the most traders. If neither Polymarket nor Manifold exist and are credible, we will use our judgment to select an alternative source.

This is question #15 in the Astral Codex Ten 2023 Prediction Contest. The contest rules and full list of questions are available here. Market will resolve according to Scott Alexander’s judgment, as given through future posts on Astral Codex Ten.

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The markets on this are not responding reasonably. Biden gave a campaign speech at the State of the Union that went well, no move. There has been a month and a half with no one declaring against him and no one making a serious move to do so. No move.

He is 62% to win the nomination according to PredictIt. Given the way the process works, most of the time that he is the nominee he is the most likely candidate at the end of 2023 - I’d say this is 95%+. If he is not the nominee, we can divide this into a few categories. If he has health or legal or other major issues that happen in 2024, he would be most likely in 2023, about 2/3rds of such issues happen in 2023 given the calendar. I’m guessing that’s roughly half the time that he isn’t the nominee. If it’s not that, then he simply gets beat in the primary. In those cases, it seems rather likely that he starts out 2024 as the favorite anyway.

So the math coming from PredictIt’s 62% is something like (60% of the 62% that he is the nominee) + (7% of the 19% that he withdraws/implodes) + (13% of the 19% that he gets challenged and loses). That’s 80%, and if anything I think the PredictIt number is low, it seems clear the Democrats are in on Biden here unless something major goes wrong. I’ve certainly given up on trying to move the needle.

I bought M$250 of yes, bringing this to 80%, with my fair something like 83%. It isn’t that correlated to the other markets and I see clear bias so I can be a little more aggressive here.

- Zvi Mowshowitz