Department of Psychology, University of Michigan, Ann Arbor, MI 48109
Proc Natl Acad Sci U S A. 2018 Feb 27;115(9):2066-2071. doi: 10.1073/pnas.1717632115. Epub 2018 Feb 9.
Averaging independent numerical judgments can be more accurate than the average individual judgment. This "wisdom of crowds" effect has been shown with large, diverse samples, but the layperson wishing to take advantage of this may only have access to the opinions of a small, more demographically homogeneous "convenience sample." How wise are homogeneous crowds relative to diverse crowds? In simulations and survey studies, we demonstrate three necessary conditions under which small socially diverse crowds can outperform socially homogeneous crowds: Social identity must predict judgment, the effect of social identity on judgment must be at least moderate in size, and the average estimates of the social groups in question must "bracket" the truth being judged. Seven survey studies suggest that these conditions are rarely met in real judgment tasks. Comparisons between the performances of diverse and homogeneous crowds further confirm that social diversity can make crowds wiser but typically by a very small margin.
平均独立的数字判断可能比平均个体判断更准确。这种“群体智慧”效应已经在大量、多样化的样本中得到了证明，但想要利用这一效应的外行人可能只能获得一小部分、人口统计学上更同质的“便利样本”的意见。同质群体相对于异质群体有多明智？在模拟和调查研究中，我们证明了在三个必要条件下，小的、具有社会多样性的群体可以胜过具有社会同质性的群体：社会认同必须预测判断，社会认同对判断的影响必须至少适中，而且所讨论的社会群体的平均估计必须“框定”正在判断的事实。七个调查研究表明，在实际的判断任务中，这些条件很少得到满足。对不同和同质群体表现的比较进一步证实，社会多样性可以使群体更明智，但通常只是很小的幅度。
