Welch t-Statistic

Problem

Return the Welch t-statistic (mean_x - mean_y) / sqrt(sx^2/nx + sy^2/ny), where sx^2 and sy^2 are sample variances. Return 0.0 when either sample has fewer than two values or the standard error is zero.

Hint

Unlike the pooled t-statistic, the standard error uses the two sample variances directly.

Test cases

case 1

in: [[1,2,3,4,5],[2,4,6,8,10]]

expected: -1.8973665961010275

case 2

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

expected: 0

case 3

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

expected: 0

case 4

in: [[10,12,14],[9,11,13]]

expected: 0.6123724356957945

case 5

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

expected: 0

Starter codePython

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

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