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Solution: Bayes and Broken Window – in a nutshell.

April 3, 2019

Solution to Exercise

There are three things to estimate. The first is the Bayesian prior probability (‘a’). This is the probability you assign to the hypothesis being true before you become aware of the new information that she had been charged on the basis of the witness evidence. The second is the probability that the new evidence would have arisen if the hypothesis was true (‘b’). It is the probability that police officer would have identified your friend if she actually did break the window. The third is the probability that the new evidence would have arisen if the hypothesis was false (‘c’). In this case, you need to estimate the probability of the police officer identifying your friend if your friend did NOT break the window.

You can now use Bayes’ Theorem to estimate the (posterior) probability that your friend broke the window based on all available information.

(Posterior) probability = ab/ [ab+c(1-a)]

From → Solutions

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