Covid Prediction Markets at Polymarketpost by Zvi · 2021-12-02T12:50:00.750Z · LW · GW · 11 comments
Will Omicron be >1% of all USA cases by the end of the year? Will the FDA give emergency use authorization or otherwise approve Paxlovid before 2022? Will the Omicron variant be marked as a Variant Of High Consequence by the CDC before 2022? Will the United States report a record high 7-day COVID-19 case average before January 1, 2022? Oracles Future Prediction Markets None 11 comments
We now have some useful prediction markets up on Covid issues, so it’s worth looking at what they say and thinking about what other markets we could generate. I encourage you to suggest additional markets in the comments, with as much detail as possible.
As I wrote a while ago, if you want prediction markets to be successful, you need five elements:
- Well Defined. The resolution mechanisms must be clear and transparent.
- Quick Resolution. The longer it takes, the less people will be interested.
- Probable Resolution. There has to be a definitive outcome most of the time.
- Limited Hidden Information. If others know what I don’t, I’m the sucker.
- Sources of Disagreement and Interest. Suckers at the table.
To these, of course, we can add an implied sixth, which is
- Real Money. Money talks, bullshit walks. Are we doing this or not?
Thus, now that we have Polymarket posting real Covid-19 markets, we have the potential to learn things that matter, with a level of resolution we can use, and I’m glad I’ve been able to help them figure out what markets to offer.
We need real money prediction markets if we want to rely on their information. I’m glad Metaculus exists and puts up some markets, and it’s good for getting some idea at all, but it is not remotely the same thing. Their main advantage is that, exactly because they don’t use real money, they can violate the five pillars and those who are inclined to participate at all will still participate because there is no cost of capital, need to invest tons of attention or worry about being the sucker when it’s for internet points.
Whereas at Polymarket, a prime motivation of liquidity providers is to use the markets to generate information, providing motivation in turn for others to come participate.
There are three new markets up, let’s check them out.
Here’s what it would look like betting $1000 or $10,000 on this respectively.
It was my suggestion to use a relatively low threshold like 1% of cases, in order to allow the market to resolve faster. There is an interesting and important question of whether Omicron would then fully displace Delta, but if Omicron goes from 0% to 1% in a month, going from 1% to 50% is a lot less exponential growth than that and should happen that much faster. The game is very much over at that point.
If the chance of 1% happening in time gets very low or very high, or there’s sufficient volume, other markets with other percentages and/or longer time horizons (or other locations) can be created to continue asking the questions that matter and improving our estimates. For now, it seems better to focus on only one market of this type, to ensure better liquidity.
It’s possible that some people are trading thinking that 1% isn’t that much, as opposed to it being the majority of the way to 50%, which is one of many possible sources of good trading.
For those in other countries like the UK, this is still mostly the question you care about, since the growth rates in both places will be highly correlated.
Currently the market is putting this result at about 67% to happen within the month, and you can bet four figures without too much slippage in price, and five figures if you’re confident enough to buy up to 77% to do so, which could easily be a good buy especially if you’re reacting quickly to new information. If you think that the market is off by a lot, I’d encourage you to come in and participate.
You can also choose to provide liquidity to the market to encourage other participants. If there’s back and forth trading you make a profit, but you’ll be on the wrong end of any permanent market moves, including the final move to 100% or 0%, unless you withdraw your funds first. It’s not an easy way to make a profit and needs to be timed and monitored carefully, but it is helping to generate a public good. Here we already have $10k in liquidity, so we’re already doing pretty well, but more always helps and we see signs of at least some back-and-forth trading.
The current market price at least seems reasonable. If I had to either buy or sell right now, I would buy, but I definitely wouldn’t move the market much doing so. It’s a tight timeline. We definitely have cases already, but there’s a wide range of potential transmission advantages for Omicron and a wide range of how many existing cases there are, and 1% in a month could go either way. Discussion in the comments is encouraged, especially backed by toy models and actual math.
As I’ve noted a few times, Paxlovid Remains Illegal. When will this change?
It’s not like this is urgent or anything. Looks like it’s a toss-up whether it will happen by the end of the year.
That’s a lot of liquidity, and it’s currently at 49%. If you can figure out the timeline first, there’s a lot of profit available. You take a hit to your price when playing big, but it’s a remarkably reasonable hit if you know something.
One month from now would be fast, slightly faster than the meeting on Molnupiravir. There doesn’t seem to be any sense of special urgency coming from the FDA. The flip side is that there is outside pressure on them on this one (that hopefully I am helping to increase somewhat), and the symbolic cost of this not stretching into 2022 seems non-trivial. With Omicron now on its way, there’s more reasons to apply pressure and to accelerate the schedule, and Metaculus had this as a coin flip before we knew about Omicron. So while this could definitely go either way, I’m guessing this is somewhat low.
The definition is: A VOHC has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants.
By the definition, it seems like there is a much higher than 10% chance that this will ultimately be a variant of high consequence. The second question then is how often that would cause the CDC to make that declaration by the end of the year? The CDC tends to always be behind the curve and hates doing useful things under uncertainty, so they’d essentially need proof.
A month seems like a long time to me. By the time Omicron is 1% of cases in the USA, it seems like we should have more than enough information to know if vaccine effectiveness against infection has declined substantially, purely through looking at the data from sequenced individuals, but will type of evidence, together with the mutations and lab analyses, be considered sufficient? That’s the question being asked here, as much as the question of the physical properties of Omicron. To win on Yes, you need to win both wagers, hence the currently low price.
I definitely wouldn’t sell here unless I knew a lot more about how the CDC operates and knew they would move sufficiently slowly or demand an impossibly high standard of evidence. I’d be worried before buying that someone else did sell down to here, and that they did have that knowledge, so I’d want to investigate further.
What we’d like to know, more than whether the CDC will officially acknowledge that Omicron is a VOHC quickly, is whether Omicron actually is such a variant, and to what extent. That would unfortunately require some combination of a longer-dated market and a means of resolution that would answer the question.
I’ll also mention the market that has the highest trading volume.
This market is less interesting than it was earlier, since it seems clear that we’re not on a trajectory to set a new record before the end of the year, but it seemed worth highlighting that volumes can get meaningful over time. Here, the volume has almost reached $250k.
The problem of things like VOHC declarations not telling us what we want to know leads us to the issue of oracles.
The best way to resolve a wager is to have a reliable source and a well-defined outcome. Unfortunately, for many of the things we care most about, this is not possible. For example, suppose we wanted to know if Omicron cases were more severe, less severe or about as severe as Delta.
In theory, we could go the Metaculus route and say something like ‘of the first five published papers of the right type in the proper journals’ and come up with a tight definition. In practice, that’s not great. It potentially takes quite a long time, still involves a bunch of judgment calls and/or complex definitions, and could end up giving us the wrong answer.
This is one of the big issues with prediction markets in practice. It’s not that useful to go betting exactly how the resolution mechanism will work, or to wait around for months or years for resolution.
Another proposal is to use a social mechanism. The Augur protocol, for example, resolves markets by splitting its entire chain in two if there’s sufficiently robust disagreement, assuming the truth-tracking chain will be the valuable one. I do not much trust that assumption, and it turns truth into a social phenomenon or one about money, influence and power. You’re now predicting social reality not physical reality. That’s exactly what prediction markets are there to prevent.
As an exercise, what would happen if there was a disputed presidential election that wasn’t as clear who was right as it was in 2020? Who wins the bets on the 2020 election if January 6 goes differently? Would the actual winner win bets, or would it be a partisan dispute resolved along partisan lines?
Who do you think is going to make the College Football Playoff this year if Alabama loses a close game to Georgia? What do you think is driving that decision? The answer depends on whether you think the group that’s deciding is trustworthy, and what criteria you think they are using. Neither of these things are at all clear.
Thus, the proposal to use a trusted person, or trusted small group, as an oracle.
We can designate a trustworthy person or small group, and let that person decide the outcome. My suggestion, with his permission, is that this person be Scott Alexander.
(If asked, I would be willing as well, but Scott seems better for this.)
He’s probably not the best possible choice, but he seems like a very good choice.
We can certainly do a lot better with someone like Scott and a well-written question than an untrustworthy Oracle using murky criteria (again, see: College Football Playoff Committee) but that only goes so far. There’s still some amount of wagering about how the Oracle will think and make its decision.
I still think it is worth doing, because it allows us to ask the questions we care about and get reasonable answers. I am confident that if it is very clear by January 1 that Omicron kills more of the people it infects, that Scott will agree with this, and that if it’s similarly clear that Omicron kills less of those people, Scott would agree with that instead. There would be cases where it was less clear, and the decision could go either way and the trading gets to be about that, but that’s a price I think we need to be willing to pay. I hope we have the interest levels necessary to justify paying it.
Future Prediction Markets
What other prediction markets about Covid-19 would provide high information value, while being sufficiently well-defined and short-term? Let’s put our brainstorming caps on and see what we can come up with. There’s a lot of willingness to help get these markets going if we can figure out the right markets to offer.
In particular, what is needed are precise questions and good resolution mechanisms and information sources. The biggest barrier to asking the questions we care about, and getting the information now, is finding a reliable way to measure that information in the future.
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