Sequential Boundary

Problem

Return the O'Brien-Fleming-style critical boundary z_alpha/sqrt(t) at information fraction t with 0 < t <= 1. Return 0.0 when t is outside that range.

Hint

The boundary is strict early and relaxes to the fixed-sample critical value at the end.

Test cases

case 1

in: [1.96,0.5]

expected: 2.7718585822512662

case 2

in: [1.96,1]

expected: 1.96

case 3

in: [1.96,0.25]

expected: 3.92

case 4

in: [2.576,0.5]

expected: 3.643014136673093

case 5

in: [1.96,0]

expected: 0

Starter codePython

def sequential_boundary(z_alpha, information_fraction):
    # Your code here
    pass

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