Diversity only marginally boosts accuracy of group's predictions

February 15, 2018 by Jared Wadley, University of Michigan
Credit: CC0 Public Domain

Diversity for boards, juries and other influential decision-making teams can help ensure that the interests of a diverse population are fairly represented and addressed.

But for situations that call for predictions or estimates, there is typically little performance benefit for using a diverse group compared with one with similar individuals, a new University of Michigan study found.

U-M psychology researchers used surveys and simulations to replicate previous findings indicating that small crowds can be wiser than individuals, but it matters far less whether the is demographically homogeneous or diverse.

The study's authors, Stephanie de Oliveira Chen and Richard Nisbett, looked at social —individual characteristics, such as gender, race, interests, religion and background—and cognitive diversity, which takes into account people's judgment or how they think.

People often believe that social diversity boosts cognitive diversity in a group. However, there can be substantial cognitive diversity within demographically homogeneous groups.

Researchers measured the social factors and judgment among study participants who completed nine judgment tasks. For example, they predicted the points that would be scored in a rival football game, votes for presidential candidates, opinions on political statements and ratings on two dozen books.

From people's estimates in the various tasks, crowds were created by averaging eight randomly selected participants—which then comprised diverse and homogeneous groups.

Among the findings:

  • The homogeneous groups produced nearly the same results as the diverse when it involved numerical judgments. Diverse groups were sometimes more accurate, but typically by a small margin.
  • People who expect social groups to think differently in these types of judgments may be erroneously stereotyping. The differences between how social groups think can be much smaller than expected.

"In other words, not all women think alike, not all liberals think alike, and so forth," said Chen, a postdoctoral researcher and study's lead author.

The researchers note that the findings do not mean that no correlate with any types of judgment. The connection between demographics and numerical is often weak, thus making it challenging to say in every situation that diverse crowds are wiser than homogenous ones, said Nisbett, the Theodore M. Newcomb Distinguished University Professor Emeritus.

The findings appear in the Proceedings of the National Academy of Sciences.

Explore further: Ethnic diversity reduces risk of market bubbles

More information: Stephanie de Oliveira et al. Demographically diverse crowds are typically not much wiser than homogeneous crowds, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1717632115

Related Stories

Ethnic diversity reduces risk of market bubbles

November 18, 2014

If they consider it at all, investors likely regard ethnic diversity as a matter of social policy. But new research by an MIT Sloan professor suggests a much more practical reason to consider diversity: compared to markets ...

Recommended for you

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

BobSage
not rated yet Feb 15, 2018
Picking the point spread between 2 teams is not going to get any better no matter what the composition of the group. If any group is better than average at picking point spreads, they would be winning millions of dollars.
philstacy9
not rated yet Feb 15, 2018
Diversity is the injection lower IQs for political reasons. Without outside help Africa and the western hemisphere might not have electricity today.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.