IV 2SLS Estimate

Problem

Return the just-identified instrumental variables (2SLS) estimate cov(z, y)/cov(z, x) using sample covariances with means. Return 0.0 when input is empty or mismatched, or when cov(z, x) is zero.

Hint

The Wald ratio is the reduced form over the first stage.

Test cases

case 1

in: [[1,2,3,4],[2,4,6,8],[1,3,5,7]]

expected: 1

case 2

in: [[1,0,1,0],[2,1,3,0],[5,2,7,1]]

expected: 2.25

case 3

in: [[1,1,1],[1,2,3],[1,2,3]]

expected: 0

case 4

in: [[],[],[]]

expected: 0

case 5

in: [[1,2],[0,0],[1,2]]

expected: 0

Starter codePython

def iv_2sls_estimate(instrument, treatment, outcome):
    # Your code here
    pass

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