Within Estimator

Problem

Return the fixed-effects (within) slope after demeaning x and y within each id: sum(xc*yc)/sum(xc^2). Return 0.0 when lengths differ, the input is empty, or the within-variation of x is zero.

Hint

Entity means absorb all time-invariant differences.

Test cases

case 1

in: [[1,2,3,4],[2,4,6,8],["a","a","b","b"]]

expected: 2

case 2

in: [[1,2,3],[1,3,5],["a","a","b"]]

expected: 2

case 3

in: [[1,2],[2,1],["a","a"]]

expected: -1

case 4

in: [[1,1,2],[1,3,5],["a","a","b"]]

expected: 0

case 5

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

expected: 0

Starter codePython

def within_estimator(x, y, ids):
    # Your code here
    pass

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