Assume that of 55 persons who take a test, 10 of the 15 people falling in the upper group on total test score and 5 of the 15 falling in the lower group on total test score pass a given item. What is the item discrimination index?
A) .17
B) .33
C) .50
D) 1.00

Question

Quizplus · Accepted Answer

The item discrimination index is calculated as (Upper Group Pass Rate - Lower Group Pass Rate) / (Total Number of Groups), which in this case is (10/15 - 5/15) / 1 = 5/15 = .33.

Assume That of 55 Persons Who Take a Test, 10