STAT 205 Lecture Notes - Lecture 3: Conditional Probability, Binary Classification, Venn Diagram
18 Sep 2016
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Use a tree diagram if events take place in a sequence: ex. The probability of a coin landing heads up and then tails up. Use a venn diagram to understand the relationship between events (if there"s a chance of both events occurring simultaneously) P(a b) is the probability of event a intersecting with event b. It includes all sample points in the intersection. The complement of a (ac or a ) is an event when a does not occur. It consists of all points not in a. *assume that p(a) 0 and p(b) 0. P(a|b) = p(ab)/p(b) = p(b|a) p(a)/(p(b|a) p(a) + p(b|a ) p(a )) Similarly, if you"re looking for p(b|a) the bayes theorem applies but with a&b flipped in each term. Finding the probability of an intersection of events. Statistical measures of the performance of a binary classification test. Measurement of the proportion of positives that are correctly identified as such.
