Item-Total Correlation

Problem

Return the corrected item-total correlation: the Pearson correlation between the item scores and the total minus the item. Return 0.0 when there are fewer than two responses, lengths differ, or either vector is constant.

Hint

Removing the item from the total prevents part-whole inflation.

Test cases

case 1

in: [[1,2,3,4],[3,5,7,9]]

expected: 1

case 2

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

expected: -1

case 3

in: [[1,1,2,2],[2,2,4,4]]

expected: 1

case 4

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

expected: 0

case 5

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

expected: 0

Starter codePython

def item_total_correlation(item, total):
    # Your code here
    pass

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