Larger crowds don’t always produce wiser decisions: Study

Mirta Galesic
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New York– Even as the world laments Britain’s vote to leave the European Union, a new study has found that larger crowds do not always produce wiser decisions.

In fact, when it comes to qualitative decisions such as “which candidate will win the election” or “which diagnosis fits the patient’s symptoms”, moderately-sized “crowds,” around five to seven randomly selected members, are likely to outperform larger ones, the study said.

Mirta Galesic
Mirta Galesic

In the real world, these moderately-sized crowds manifest as physician teams making medical diagnoses; top bank officials forecasting unemployment, economic growth, or inflation; and panels of election forecasters predicting political wins.

“When we ask ‘how many people should we have in this group?’ the impulse might be to create as big a group as possible because everyone’s heard of the wisdom of crowds,” said one of the researchers, Mirta Galesic, Professor at Santa Fe Institute in the US.

But in many real world situations, it is actually better to have a group of moderate size, Galesic noted.

The researchers mathematically modelled group accuracy under different group sizes and combinations of task difficulties.

They found that in situations similar to a real world expert panel, where group members encounter a combination of mostly easy tasks peppered with more difficult ones, small groups proved more accurate than larger ones.

“Organisations might take this research to heart when designing groups to solve a series of problems,” Galesic said.

The research was published in Decision, a journal of the American Psychological Association.

What about voting as a means of determining the majority opinion of a populace?

“These results, of course, do not mean that we should abandon large scale referendums like Brexit and national elections,” Galesic added.

Choices between different policies and candidates often do not have a ‘right’ and a ‘wrong’ answer: different people simply prefer different things, and the outcomes of these decisions are complex, with a spectrum of consequences, she said.

“It is important to account for everyone’s opinion about the general direction in which they want their country to go — including underrepresented groups,” Galesic noted.

“But when it comes to decisions with a more clear ‘right’ and ‘wrong’ answer — where everyone can, at least after the fact, agree that one course of action was better than the other — then moderately sized groups of experts can often be better than larger groups or individuals,” she pointed out.


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