Wisdom of Crowds

Joseph Reagle

Stupid crowds


“Anyone taken as an individual is tolerably sensible and reasonable – as a member of a crowd, he at once becomes a blockhead.” – Bernard Baruch

“Madness is the exception in individuals but the rule in groups.” – Friedrich Nietzsche

“I do not believe in the collective wisdom of individual ignorance.” – Thomas Carlyle (Surowiecki 2004)

Wisdom of crowds

Jelly beans

Others egs?

Cereal (2-stage)

  • 467

Are we talking about organizations?

Problem domain?


for which there is a single answer


by which an optimal group solution arises from individual self-interest, but requires feedback


for which an optimal group solution requires trust and group orientation, i.e., social structure/culture

WoC requires?

WoC requires

  1. diversity of opinion (private info)
  2. independence (un-influenced)
  3. decentralization (local knowledge and equal weight)
  4. aggregation (private judgment -> collective decision) (Surowiecki 2004, p. 10)

Evidence for a collective intelligence factor in the performance of human groups

Measures of “collective intelligence” (c) based on tasks such as visual puzzles, brainstorming, collective moral judgments, and negotiating over limited resources. In the first study (of 40 3-person groups) average and maximum intelligence scores of individual group members does not correlate with c. When combining the findings of the two studies, there’s a moderate correlation between c and average/highest-scoring intelligence, but “c was still a much better predictor of group performance on the criterion tasks then the average or maximum individual intelligence.” In turn, three factors were significantly correlated with c: average social sensitivity, conversational turn-taking, and the proportion of females in the group (these are likely related). (WoolleyEtal 2010)

How to ascertain and create diversity?

Exploring vs exploiting



Lines (1951)

Elevator (1962)

When are individuals/experts superior (e.g., Kasparov, Einstein, Jobs)?


In a group of 3 ~ 4 identify three cases where WoC would work, and three were it wouldn’t.