The Real Power of Artificial Markets
The Real Power of Artificial Markets
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人工市场的真正力量
作者：
David M. Pennock;S. Lawrence;C. Lee Giles;F. A. Nielsen
评估未来事件的概率是科学政策制定者经常面临的问题。例如，欧洲粒子物理实验室 CERN 最近必须判断发现希格斯玻色子的概率是否足够高，以证明延长其对撞机的运行是合理的（参见《科学》，9 月 22 日，第 2014 页和 9 月 29 日，第 2260 页）。在 Foresight Exchange (FX) 网站 (http://www.ideosphere.com/)，交易者实际上可以押注未解决的科学问题的结果，包括物理学家是否会在 2005 年发现希格斯玻色子。该证券的当前价格（截至 1 月 24 日为 0.77）可以被视为市场对粒子发现概率的评估。外汇只是一个游戏，用游戏币（外汇美元）运行。实证研究 (1)、实验室调查 (2) 和政策建议 (3) 认为，真实货币证券的价格确实构成了准确的可能性，因为交易者有强烈的（货币）动机来利用相关信息。但是，我们能否合理地相信外汇价格的准确性，因为外汇价格完全是通过虚拟货币市场游戏中的竞争来确定的？在某种程度上，是的。我们发现外汇价格与观察到的结果频率密切相关。我们收集了 161 种到期证券的历史价格信息，对应于已明确回答“是”或“否”的问题，记录到期前 30 天的价格，按价格对证券进行排序，并将其分为六个价格范围。该图绘制了每组观察到的频率（“是”证券的实际数量除以总数）与平均价格（以外汇美元计算）的关系。假设结果是具有统一先验的独立伯努利试验，误差线显示 95% 的置信区间。我们在另一个名为好莱坞证券交易所 (http://www.hsx.com/) 的虚拟货币市场中发现了类似的准确性。奥斯卡、艾美奖和格莱美奖的证券价格与实际获奖结果频率密切相关，电影股票的价格可以准确预测真实的票房结果。
Assessing the probabilities of future events is a problem often faced by science policymakers. For example, CERN, the European laboratory for particle physics, recently had to judge whether the probability of discovering a Higgs boson was high enough to justify extending the operation of its collider (see Science, 22 Sept., p. 2014 and 29 Sept., p. 2260). At the Foresight Exchange (FX) Web site (http://www. ideosphere.com/), traders can actually bet on the outcomes of unresolved scientific questions, including whether physicists will discover the Higgs boson by 2005. The going price of the security (0.77 as of 24 Jan) can be seen as the market’s assessment of the probability of the particle’s discovery. FX is only a game, run with play money (FX dollars). Empirical studies (1), laboratory investigations (2), and policy proposals (3) argue that prices of real-money securities do constitute accurate likelihoods, since traders have strong (monetary) incentives to leverage pertinent information. But can we place legitimate credence on the accuracy of FX prices, which are determined solely through competition in a play-money market game? To an extent, yes. We find that FX prices strongly correlate with observed outcome frequencies. We collected historical price information for 161 expired securities, corresponding to questions that had been definitively answered “yes” or “no”, recorded prices thirty days before expiration, sorted securities by price, and grouped them into six price ranges. The figure plots observed frequency (the actual number of “yes” securities divided by the total number) versus average price (in FX dollars) for each group. Error bars display 95% confidence intervals, under an assumption that outcomes are independent Bernoulli trials with a uniform prior. We find similar accuracy in another play-money market called the Hollywood Stock Exchange (http://www.hsx.com/). Prices of securities in Oscar, Emmy, and Grammy awards correlate well with actual award outcome frequencies, and prices of movie stocks accurately predict real box office results.