How strongly should she believe the hypothesis? Should she have surgery? We can answer these questions by rewriting Bayes’s rule as follows: (Updated probability of D) = P(D | T) = (likelihood ratio) × (prior probability of D)(3.2) where the new term “likelihood ratio” is given by P(T | D)/P(T). It measures how much more likely the positive test is in people with the disease than in the general population.
