Appendix E Don’t Bet on the Super Bowl
This appendix contains a supporting example for probability and expected value, using the moneyline odds format common in American sports betting.
If you have studied probability, you might be familiar with fractional odds, which represent the ratio of the probability something happens to the probability it doesn’t. For example, if the Seahawks have a 75% chance of winning the Super Bowl, they have a 25% chance of losing, so the ratio is 75 to 25, sometimes written 3:1 and pronounced “three to one”.
But if you search for “the odds that the Patriots will win the Super Bowl”, you will find the odds expressed as a number like +195 or -240. That’s called a moneyline, and it represents the expected return of a wager. Specifically:
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A positive moneyline like +195 means that if you bet $100 and win, you get $195 back (plus your $100 bet).
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A negative moneyline like -240 means that if you bet $240 and win, you get $100 back (plus your $240 bet).
