An item-discrimination index is used on an ability test
A) to determine whether items are measuring what they are designed to measure.
B) to measure the difference between how many high scorers and how many low scorers answered the item correctly.
C) to estimate how predictive the item is of the testtaker's future performance.
D) to measure the difference between how many median scorer and how many low scorers answered the item correctly.

Question

Quizplus · Accepted Answer

The item-discrimination index measures the extent to which an item is able to distinguish between high and low scorers on a test. It provides information about how well an item is able to discriminate among test-takers of different levels of ability, which is important when evaluating the quality of a test. Option A is incorrect because the index does not directly measure whether items are measuring what they are designed to measure. Option C is incorrect because the item-discrimination index is not used to estimate the predictive validity of an item or test. Option D is incorrect because the index does not specifically measure the difference between median and low scorers.

An Item-Discrimination Index Is Used on an Ability Test