Risk Difference Confidence Interval

Problem

Return the Wald confidence interval for the risk difference a/(a+b) - c/(c+d) with standard error sqrt(p1(1-p1)/n1 + p2(1-p2)/n2). Return [0.0, 0.0] when either group is empty.

Hint

The two groups are treated as independent samples.

Test cases

case 1

in: [20,80,10,90,1.96]

expected: [0.0020000000000000018,0.198]

case 2

in: [10,10,10,10,1.96]

expected: [-0.3099032106965012,0.3099032106965012]

case 3

in: [5,0,1,1,1.96]

expected: [-0.19296464556281656,1.1929646455628165]

case 4

in: [0,10,5,5,2]

expected: [-0.816227766016838,-0.18377223398316206]

case 5

in: [0,0,1,1,1.96]

expected: [0,0]

Starter codePython

def risk_difference_ci(a, b, c, d, z_crit):
    # Your code here
    pass

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