Lesson #4 taught the standard way to strip vig from sportsbook odds — proportional devigging. It works on most markets. It doesn't work on all of them. This lesson is the longer story: three devigging methods, when each is right, and the one you should default to.
The setup
Every devigging method does the same job: takes the implied probabilities from a vigged market and converts them into a fair-probability estimate that sums to 100%. They differ in how they remove the vig.



