|via Gerald G/WikimediaCommons|
On Oct. 21 Andrew Gelman asked on his blog, "What's the probability that Daniel Murphy hits a home run tonight?" (in a record-setting 6th straight playoff game):
He posted the answer as 20% and then, at the coaxing of some commenters, lowered it to 15%.
Then... later that evening, he raised the probability to 1... because of course Murphy (of the New York Mets) did just that, hit a home run in the 8th inning (playing against the Chicago Cubs, surely a major factor ;-)
And so, in a matter of hours the "probability" of something went from 20% to 15% to 100%... a nice demonstration of why, given human complexity, "probability" is often a near-meaningless concept when it comes to individual behavior and events.