D
On March 7, 1907, the English statistician Francis Galton published a paper which illustrated what has come to be known as the “wisdom of crowds” effect. The experiment of estimation he conducted showed that in some cases, the average of a large number of independent estimates could be quite accurate.
This effect capitalizes on the fact that when people make errors, those errors aren’t always the same. Some people will tend to overestimate, and some to underestimate. When enough of these errors are averaged together, they cancel each other out, resulting in a more accurate estimate. If people are similar and tend to make the same errors, then their errors won’t cancel each other out. In more technical terms, the wisdom of crowds requires that people’s estimates be independent. If for whatever reasons, people’s errors become correlated or dependent, the accuracy of the estimate will go down.
But a new study led by Joaquin Navajas offered an interesting twist (转折) on this classic phenomenon. The key finding of the study was that when crowds were further divided into smaller groups that were allowed to have a discussion, the averages from these groups were more accurate than those from an equal number of independent individuals. For instance, the average obtained from the estimates of four discussion groups of five was significantly more accurate than the average obtained from 20 independent individuals.
In a follow-up study with 100 university students, the researchers tried to get a better sense of what the group members actually did in their discussion. Did they tend to go with those most confident about their estimates? Did they follow those least willing to change their minds? This happened some of the time, but it wasn’t the dominant response. Most frequently, the groups reported that they “shared arguments and reasoned together”. Somehow, these arguments and reasoning resulted in a global reduction in error. Although the studies led by Navajas have limitations and many questions remain, the potential implications for group discussion and decision-making are enormous.
What is paragraph 2 of the text mainly about?
主旨大意题。根据第二段内容“This effect capitalizes on the fact that when people make errors, those errors aren’t always the same. Some people will tend to overestimate, and come to underestimate. When enough of these errors are averaged together, they cancel each other out, resulting in a more accurate estimate. If people are similar and tend to make the same errors, then their errors won’t cancel each other out. In more technical terms, the wisdom of crowds requires that people’s estimates be independent. If for whatever reasons, people s errors become correlated or dependent, the accuracy of the estimate will go down. (这种效应利用了这样一个事实，即当人们犯错误时，这些错误并不总是相同的。有些人常常会高估，或者低估。当这些误差中有足够多的误差被平均在一起时，它们会相互抵消，从而产生更准确的估计。如果相似的人倾向于犯同样的错误，那么他们的错误不会相互抵消。从更专业的角度来说，群众的智慧要求人们的估计是独立的。如果由于任何原因，人们的错误变得相关或依赖，估计的准确性就会下降)”可知，本段阐述了人们所犯的错误不总是相同的，各不相同的误差平均在一起，相互抵消就会产生更准确的估计，讨论了独立估计的平均如何由于误差的消除而产生更准确的预测。因此本段主要解释了“群体智慧”效应这一现象的基本逻辑。故选B。
Navajas’ study found that the average accuracy could increase even if ________.
细节理解题。根据第二段的“In more technical terms, the wisdom of crowds requires that people’s estimates be independent. (从更专业的角度来说，群众的智慧要求人们的估计是独立的)”和第三段的“The key finding of the study was that when crowds were further divided into smaller groups that were allowed to have a discussion, the averages from these groups were more accurate than those from an equal number of independent individuals. For instance, the average obtained from the estimates of four discussion groups of five was significantly more accurate than the average obtained from 20 independent individuals. (这项研究的关键发现是，当人群被进一步划分为允许进行讨论的小组时，这些小组的平均值比同等数量的独立个体的平均值更准确。例如，从四个五人讨论组的估计中获得的平均值明显比从20个独立个体获得的平均值更准确)”可知，人们在没有独立的情况下，分成更小群体，平均值是更准确的，说明即使在估计数字并非完全独立的情况下，准确率提高也是可以做到的。故选D。
What did the follow-up study focus on?
推理判断题。根据第四段的“In a follow-up study with 100 university students, the researchers tried to get a better sense of what the group members actually did in their discussion. Did they tend to go with those most confident about their estimates? Did they follow those least willing to change their minds? (在一项针对100名大学生的后续研究中，研究人员试图更好地了解小组成员在讨论中的实际行为。他们是否倾向于选择那些对自己的估计最有信心的人？他们追随那些最不愿意改变主意的人吗)”可知，在后续研究中，研究人员试图更好地了解小组成员在讨论中实际做了什么。结合两个问题，因此可知后续研究的重点是小组内的讨论过程。故选C。
What is the author’s attitude toward Navajas’ studies?
推理判断题。根据最后一段内容“Although the studies led by Navajas have limitations and many questions remain, the potential implications for group discussion and decision-making are enormous. (尽管Navajas领导的研究有局限性，仍存在许多问题，但对小组讨论和决策的潜在影响是巨大的)”可知，作者认为虽然Navajas领导的研究有局限性也存在许多问题，但对小组讨论和决策的潜在影响巨大。因此推断作者对于Navajas的研究表示一定的赞许和支持。故选D。