# Stuck on Bayes Theorem

I'm working on a example understanding Bayes, and wondering if my thought process is correct. So I have three users, and true or false if they own Nike or Reebok shoes, or both. I want to calculate the probability of Reebok's if they own Nike's. Here is my data:

User  | Nike  | Reebok
Jesse | true  | false
Jake  | false | true
John  | true  | true   - only user with both


Here is how I'm attempting to do this:

1) P(both/just Reebok) = 1/2 = 50%
2) P((total user with either - both)/total user with either = (3-1)/3 = 67% 3) Normalize P = 50%/(50%+67%) = 43%

So the result would be if a user owned Nike's, they have a 43% probability of owning Reebok's.

• I don't see anything in this question that is Bayesian – Glen_b Aug 11 '15 at 3:27
• There is no such a thing as "Naive Bayes Theorem" there is "Naive Bayes Algorithm" and "Bayes theorem". I edited your title. – Tim Aug 11 '15 at 12:20