The expected value or expectation is the (weighted) average of all the possible outcomes of an event, weighed by their probability. For example, when you roll a die, the expected value is (1+2+3+4+5+6)/6 = 3.5.
(Since a die doesn’t even have a face that says 3.5, this illustrates that very often, the “expected value” isn’t a value you actually expect.)
Anyone objects to deleting this page? There seems to be no significance to it, it’s even not linked from anywhere. --Vladimir Nesov 23:03, 8 July 2009 (UTC)
Video to demonstrate how to NOT think about expected value
http://youtu.be/kuXIpxoMYtc?t=20s
George Gervin (NBA Legend) says that the 3-point shot is the worst shot in basketball. His argument is basically that 3-point percentages are almost always lower than 2-point percentages. He seems to not give any weight to the fact that 3-point shots provide you with one extra point...
Perhaps the example should include probabilities
The example with the 6-sided die doesn’t explicitly show how probabilities are part of the calculation. Perhaps the example should do this.