Enter the number of upper group students who answered correctly and the number of lower group students who answered correctly, as well as the total number of students in each group into the calculator to determine the Discrimination Index.
Discrimination Index Formula
The following formula is used to calculate the Discrimination Index.
DI = (U - L) / N
Variables:
- DI is the Discrimination Index
- U is the number of upper group students who answered correctly
- L is the number of lower group students who answered correctly
- N is the total number of students in each group
To calculate the Discrimination Index, subtract the number of lower group students who answered correctly from the number of upper group students who answered correctly. Then, divide the result by the total number of students in each group.
What is a Discrimination Index?
A Discrimination Index is a statistical measure used in educational testing to determine the effectiveness of a particular question in differentiating between high and low scorers. It indicates how well a question can distinguish between students who have a good overall understanding of the tested subject and those who do not. A high discrimination index suggests that the question is effective at distinguishing between these groups, while a low index suggests it is not.
How to Calculate Discrimination Index?
The following steps outline how to calculate the Discrimination Index.
- First, determine the number of upper group students who answered correctly (U).
- Next, determine the number of lower group students who answered correctly (L).
- Next, determine the total number of students in each group (N).
- Next, gather the formula from above = DI = (U – L) / N.
- Finally, calculate the Discrimination Index.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
U: number of upper group students who answered correctly = 45
L: number of lower group students who answered correctly = 30
N: total number of students in each group = 100
