Table 1.

The wisdom of crowd effect exists with respect to the geometric mean but not with respect to the arithmetic mean

Wisdom-of-crowd aggregation
QuestionTrue valueArithmetic meanGeometric meanMedian
1. Population density of Switzerland1842,644 (+1,337.2%)132 (−28.1%)130 (−29.3%)
2. Border length, Switzerland/Italy7341,959 (+166.9%)338 (−54%)300 (−59.1%)
3. New immigrants to Zurich10,06726,773 (+165.9%)8,178 (−18.8%)10,000 (−0.7%)
4. Murders, 2006, Switzerland198838 (+323.2%)174 (−11.9%)170 (−14.1%)
5. Rapes, 2006, Switzerland6391,017 (+59.1%)285 (−55.4%)250 (−60.9%)
6. Assaults, 2006, Switzerland9,272135,051 (+1,356.5%)6,039 (−34.9%)4,000 (−56.9%)
  • The aggregate measures arithmetic mean, geometric mean, and median are computed on the set of all first estimates regardless of the information condition. Values in parentheses are deviations from the true value as percentages.