The Importance Of Item Analysis

Two years ago, our headmistress called an urgent meeting where one of our district education supervisor was coming down to our school to give a talk on ways to improve the qualities of our students who were going to sit for their UPSR Exam. 

I still remember that one of the methods that can be used to improve their qualities after they done their monthly test is item analysis. But, being the greenhorn that I was, I pay less attention on the details and simply carry forward to "my" style of teaching.

It was not until this year that I "stumbled" the "item analysis" thing again during my Measurement and Assessment in Education class in OUM. This time, I had no chance to avoid it since one of my assignment's question needs me to conduct an item analysis on a given test to my sample students.

Since I put serious effort on undertaking my assignment, I really had to learn from the beginning about item analysis. At first, I find that item analysis is not worthwhile because most of my colleagues said that doing it is time-consuming and does not give a big impact on student learning as they are just numbers. But, when my tutor explains to me that item analysis is a crucial step to improve the quality of students in test-taking, it picked up my interest as I was almost ran out of idea how to improve my students in Science in the quickest and reliable way as part of their preparation in facing the UPSR exam.

After sourcing outside information, this item analysis that I have been doing for my student is actually known as the Toolkit Evaluation method. So, here I know that what I do is not anything new but proves to be a reliable method that can improve learning. (You can click here to get more info about Toolkit Evaluation).


By far, I've been using item analysis to get another two important data, which are difficulty index and discrimination index. Both of these data are actually the keystone to further improve the quality of question given to student, which supports better student learning through test-taking.


Difficulty index (of an item) is defined as the percentage of the overall students that can answer correctly the given question. The higher the number of index or nearer to 1, the easier the question is while the lower the number of index or nearer to 0, the harder the question is.

The formula used to calculate difficulty index is as below:

Difficulty index = number of total correct answer answered / number of total student answered

Here, the teacher can use the information to specify students' learning on learning topic that are related to the questions that has low index.

Discrimination index (on an item) is defined as the ability of a questionnaire to discriminate between high achieving students and low achieving students. A higher number of the index or nearer to 1 signifies that the question is reliable to be used to discriminate high and low achieving students while a lower score indicates otherwise.

To calculate the formula of discrimination index requires a few steps to be done. First, the total number of students sitting the test must be divided into three groups. The first 27% of the highest marks will be categorized as "high achievers". Then, 46% of the next highest marks students will be grouped into "medium achievers". The remaining students will be grouped into "low achievers".

After the division of groups is done, then we can use the formula below to calculate the discrimination index.

Discrimination Index = rU - rL / 0.5 (tU+tL)


rU = Number of high achievers who answers the given question correctly.
rL = Number of low achievers who answers the given question correctly


tU = Total number of high achieving students
tL = Total number of low achieving student


Because of these benefits, an item analysis is considered to be one of the important factor that can be used to improve students test taking abilities.