Aggregate judgments of groups can exceed individual expert judgments.
Galton's 1907 ox-weight competition: 787 guesses averaged 1,197 pounds against an actual 1,198. The conditions are strict — independence, diversity, and an aggregation mechanism — and correlated errors destroy it.
In practice
- A team asked to estimate a project independently and then averaged lands closer than any member; the same team asked in a meeting converges on whoever spoke first.
- A village fete sweepstake on the weight of a cake collects sixty guesses, and the mean beats the baker's.
- Further reading
- Wikipedia
- Subject
- Decision-making & Reasoning
- Essay
- The catalogue of predictable errors