How do researchers calculate the discrimination index?
A) They calculate the difference between the percentage of upper performers and the percentage of lower performers who responded correctly.
B) They calculate the percentage of test takers who answered the item correctly.
C) They compare the percentage of test takers who answered the item correctly by demographic group.
D) They develop a matrix that contains the results of the item analyses for each item and calculate a score by adding the matrix columns.

Question

Quizplus · Accepted Answer

The discrimination index is calculated by finding the difference between the percentage of upper performers (those who score well on the test overall) and the percentage of lower performers (those who score poorly on the test overall) who responded correctly to a specific test item. This indicates whether the item is easier for higher performing test-takers and more difficult for lower performing test-takers, which provides information about the quality of the item.

How Do Researchers Calculate the Discrimination Index