乌克兰战争爆发后，预测市场对战争走向的预测发生了显著变化。Metaculus和Polymarket等平台上的预测显示，乌克兰抵抗俄罗斯的可能性越来越大，而俄罗斯占领基辅的可能性则大幅下降。此外，预测市场对俄罗斯入侵其他国家、普京下台以及乌克兰总统泽连斯基下台的可能性也发生了变化。

🤔 **乌克兰抵抗能力增强**：预测市场最初认为俄罗斯占领乌克兰的可能性很高，但随着战争的进展，预测市场对乌克兰抵抗能力的信心不断增强。例如，Metaculus上“基辅将在2022年4月前被俄罗斯占领”的概率从69%下降到14%。

📈 **预测市场的不稳定性**：尽管预测市场对乌克兰的抵抗能力更加乐观，但预测市场本身也存在一些问题。例如，Metaculus和Polymarket上的预测数据显示出一种“单调下降”的趋势，这表明市场可能存在效率问题，未能及时反映新的信息和变化。

🧐 **预测市场机制的影响**：预测市场上的预测数据受到多种因素的影响，包括市场参与者的判断、信息更新机制以及市场本身的结构。预测市场可能存在一些缺陷，例如未能及时反映新的信息，导致预测数据出现偏差。

📊 **预测市场作为信息来源的局限性**：预测市场可以提供对未来事件的预测，但这些预测并非绝对准确，也并非唯一的参考来源。预测市场数据需要结合其他信息和分析才能做出更全面的判断。

https://astralcodexten.substack.com/p/mantic-monday-31422

Changes in Ukraine prediction markets since my last post February 28:

Will Kiev fall to Russian forces by April 2022?: 69% —→ 14%

Will at least three of six big cities fall by June 1?: 71% —→ 70%

Will World War III happen before 2050?: 20% —→21%

Will Russia invade any other country in 2022?: 12% —→10%

Will Putin still be president of Russia next February?: 71% —→ 80%

Will 50,000 civilians die in any single Ukrainian city?: 8% —→ 12%

Will Zelinskyy no longer be President of Ukraine on 4/22?: 63% —→20%

If you like getting your news in this format, subscribe to the Metaculus Alert bot for more (and thanks to ACX Grants winner Nikos Bosse for creating it!)

Numbers 1 and 7 are impressive changes! (it’s interesting how similarly they’ve evolved, even though they’re superficially about different things and the questions were on different prediction markets). Early in the war, prediction markets didn’t like Ukraine’s odds; now they’re much more sanguine.

Let’s look at the exact course:

This is almost monotonically decreasing. Every day it’s lower than the day before.

How suspicious should we be of this? If there were a stock that decreased every day for twenty days, we’d be surprised that investors were constantly overestimating it. At some point on day 10, someone should think “looks like this keeps declining, maybe I should short it”, and that would halt its decline. In efficient markets, there should never be predictable patterns! So what’s going on here?

Maybe it’s a technical issue with Metaculus? Suppose that at the beginning of the war, people thought there was an 80% chance of occupation. Lots of people predicted 80%. Then events immediately showed the real probability was more like 10%. Each day a couple more people showed up and predicted 10%, which gradually moved the average of all predictions (old and new) down. You can see a description of their updating function here - it seems slightly savvier than the toy version I just described, but not savvy enough to avoid the problem entirely.

But Polymarket has the same problem: