Two-Sample Pooled t-Statistic

Problem

Return the pooled two-sample t-statistic (mean_x - mean_y) / (sp*sqrt(1/nx + 1/ny)), where sp^2 = ((nx-1)sx^2 + (ny-1)sy^2)/(nx+ny-2). Return 0.0 when either sample has fewer than two values or the standard error is zero.

Hint

Pool the sums of squares first and divide by nx + ny - 2.

Test cases

case 1

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

expected: -1.8973665961010275

case 2

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

expected: -3.6742346141747673

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

expected: 0

Starter codePython

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

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