Item Discrimination

Problem

Return the discrimination index: the proportion answering the item correctly in the top n_each examinees by total score minus that proportion in the bottom n_each. Return 0.0 when n_each <= 0, 2*n_each exceeds n, or lengths differ.

Hint

High-achieving examinees should get the item right more often.

Test cases

case 1

in: [[1,1,1,0,0,0],[6,5,4,3,2,1],2]

expected: 1

case 2

in: [[0,0,0,1,1,1],[6,5,4,3,2,1],2]

expected: -1

case 3

in: [[1,0,1,0,1,0],[5,4,3,2,1,0],2]

expected: 0

case 4

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

expected: 0

case 5

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

expected: 0

Starter codePython

def item_discrimination(item_scores, total_scores, n_each):
    # Your code here
    pass

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