论文标题

人群的智慧:一无所有

Wisdom of crowds: much ado about nothing

论文作者

Reia, Sandro M., Fontanari, José F.

论文摘要

令人困惑的观念是,数量大小的独立估计值的组合导致了非常准确的预测,这比任何一个或至少在大多数个体估计中都优于任何人,被称为人群的智慧。在这里,我们使用费城联邦储备银行对专业预测数据库的调查来面对这种现象的统计和心理物理解释。总体而言,我们发现数据不支持人群智慧的任何拟议解释。特别是,我们发现估计值的方差(或多样性)与人群误差之间存在正相关,并与对多样性预测定理的某些解释分歧。此外,相反的是心理物理增强Quincunx模型的预测,我们发现估计值的偏差没有提供有关人群错误的信息。更重要的是,我们发现人群在不到2%的预测中击败了所有个人,并且在不到70%的预测中击败了大多数人,这意味着,随机选择的个人的表现可能会比人群更好。这些结果与由公正的预报者组成的非天然人群的表现形成鲜明对比,这些预报几乎在几乎所有的预测中都击败了大多数人。现实世界中的人群比其成员的中等统计优势并不能证明其智慧的合理性,这很可能是选择性关注谬误的产物。

The puzzling idea that the combination of independent estimates of the magnitude of a quantity results in a very accurate prediction, which is superior to any or, at least, to most of the individual estimates is known as the wisdom of crowds. Here we use the Federal Reserve Bank of Philadelphia's Survey of Professional Forecasters database to confront the statistical and psychophysical explanations of this phenomenon. Overall we find that the data do not support any of the proposed explanations of the wisdom of crowds. In particular, we find a positive correlation between the variance (or diversity) of the estimates and the crowd error in disagreement with some interpretations of the diversity prediction theorem. In addition, contra the predictions of the psychophysical augmented quincunx model, we find that the skew of the estimates offers no information about the crowd error. More importantly, we find that the crowd beats all individuals in less than 2% of the forecasts and beats most individuals in less than 70% of the forecasts, which means that there is a sporting chance that an individual selected at random will perform better than the crowd. These results contrast starkly with the performance of non-natural crowds composed of unbiased forecasters which beat most individuals in practically all forecasts. The moderate statistical advantage of a real-world crowd over its members does not justify the ado about its wisdom, which is most likely a product of the selective attention fallacy.

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