Posterior After Positive Test

Problem

With prevalence p, sensitivity se, and specificity sp, the posterior probability of disease given a positive test is se * p / (se * p + (1 - sp)(1 - p)).

Given sensitivity, specificity, and prevalence, return the posterior.

Hint

The denominator is the total probability of a positive test.

Test cases

case 1

in: [0.9,0.9,0.01]

expected: 0.08333333333333336

case 2

in: [0.99,0.95,0.1]

expected: 0.6874999999999998

case 3

in: [1,1,0.5]

expected: 1

Starter codePython

def posterior_after_positive_test(sensitivity, specificity, prevalence):
    # Your code here
    pass

3 test cases · run your code against them in the editor