Confidence Interval for a Proportion

Problem

Return the Wald confidence interval [p - z*sqrt(p(1-p)/n), p + z*sqrt(p(1-p)/n)] for a binomial proportion, with p = successes/n. Return [0.0, 0.0] when n <= 0.

Hint

At p = 0 or 1 the interval collapses to a point.

Test cases

case 1

in: [45,100,1.96]

expected: [0.35249123116355124,0.5475087688364488]

case 2

in: [0,50,1.96]

expected: [0,0]

case 3

in: [50,100,1.645]

expected: [0.41775,0.58225]

case 4

in: [10,10,1.96]

expected: [1,1]

case 5

in: [5,20,2]

expected: [0.05635083268962915,0.44364916731037085]

Starter codePython

def ci_proportion(successes, n, z_crit):
    # Your code here
    pass

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