Statistics 101— Bayes’ Theorem

Bayes’s theorem (alternatively Bayes’s law or Bayes’s rule) describes the probability of an event, based on prior knowledge of conditions that might be related to the event.

Dependent Events where what happens depends on what happened before, such as taking cards from a deck makes fewer cards each time.

Monty Hall problem

Monty Hall problem is a counter-intuitive statistics puzzle:

• There are 3 doors, behind which are two goats and a car.
• You pick a door (call it door A). You’re hoping for the car of course.
• Monty Hall, the game show host, examines the other doors (B & C) and opens one with a goat. (If both doors have goats, he picks randomly.)

Here’s the game: Do you stick with door A (original guess) or switch to the unopened door? Does it matter?

If you switch doors you’ll win 2/3 of the time!