What is the value of the item-discrimination index for an item answered correctly by an equal number of students in the higher- and lower-scoring groups?
A) -1
B) +1
C) .50
D) 0

Question

Quizplus · Accepted Answer

The item-discrimination index (D) is calculated by subtracting the proportion of lower-scoring students who answered the item correctly from the proportion of higher-scoring students who answered the item correctly. If an equal number of students in both groups answered the item correctly, then the proportion in both groups is the same, resulting in a difference of zero (0). Therefore, the value of the item-discrimination index would be zero, making choice D the correct answer.

What Is the Value of the Item-Discrimination Index for an Item