Cramer-Rao Lower Bound

Problem

For n independent samples from N(mu, sigma^2) with known variance, the Cramer-Rao lower bound on the variance of any unbiased estimator of mu is sigma^2 / n.

Given sigma and n, return that bound.

Hint

More samples or a smaller variance lower the bound quadratically.

Test cases

case 1

in: [1,1]

expected: 1

case 2

in: [2,4]

expected: 1

case 3

in: [0.5,10]

expected: 0.025

case 4

in: [3,2]

expected: 4.5

Starter codePython

def cramer_rao_bound(sigma, n):
    # Your code here
    pass

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