Bayes Theorem

Description:

Bayes Theorem provides a method for calculating P(h | D), denoting the probability of h being correct, given a specific data set D.

Let
  • P be a probability distribution,
  • h be a hypothesis and
  • D be a data set.
If we know
  • P(h), the probability of hypothesis h being correct,
  • P(D), the probability of data set D being observed, and
  • P(D | h), the probability of observing D, under the assumption of h being correct,
then Bayes Theorem provides a method for calculating P(h | D), denoting the probability of h being correct, given a specific data set D.

Bayes Theorem:

P(h | D) = P(D | h) * P(h) / P(D)

An application of Bayes Theorem:
  • Given a data set D, find a hypothesis h ∈ H with highest posteriori probability P(h | D).
  • Method: Chose a hypothesis h ∈ H that maximizes the expression P(D | h) * P(h).