(35S) Conditional Probabilities - Bayes Formula - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Software Libraries ( /forum-10.html)+--- Forum: General Software Library ( /forum-13.html)+--- Thread: (35S) Conditional Probabilities - Bayes Formula ( /thread-2496.html) |

(35S) Conditional Probabilities - Bayes Formula - Gerald H - 11-25-2014 03:00 PM
Bayes’ formula is useful for calculating conditional probabilities. If we set p(E) = A = .001 as the probability of a member of the population having a certain illness E, p(F|E) = B = .99 as the probability of a positive result for the illness test F if the member has the illness E, p(F|-E) = C = .05 as the probability of a positive result for the illness test F if the member does NOT have the illness E, a so-called false positive, then the formula D = A * B / ( A * B + ( 1 – A) * C ) can be used to calculate p(E|F) = D ie the probability of having the illness E if the test F is positive, which for the given data is .019 |