One of the purest and most fascinating examples of the “wisdom
of crowds” in action comes courtesy of a unique online contest
called ProbabilitySports run by mathematician Brian Galebach. In
the contest, each participant states how likely she thinks it is
that a team will win a particular sporting event. For example,
one contestant may give the Steelers a 62% chance of defeating
the Seahawks on a given day; another may say that the Steelers
have only a 44% chance of winning. Thousands of contestants give
probability judgments for hundreds of events: for example, in
2004, 2,231 ProbabilityFootball participants each recorded
probabilities for 267 US NFL Football games (15-16 games a week
for 17 weeks). An important aspect of the contest is that
participants earn points according to the quadratic scoring
rule, a scoring method designed to reward accurate probability
judgments (participants maximize their expected score by
reporting their best probability judgments). This makes
ProbabilitySports one of the larges