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Educational Measurement and Evaluation

Notes • Criteria for Item-analysis : The purpose of item-analysis is to select suitable and good test
items from the many items the test-maker has made.
• This decision is taken on two bases :
(i) Difficulty index, and
(ii) Discrimination index or validity index.
• Process of Item-analysis
• To undertake item-analysis, at first the test is administered to a sample of those individuals
or students for whom it has been constructed. After that, all test papers are marked and the
following processes are sequentially followed :
(i) Test-papers or answer-sheets are arranged in the ascending order of scores.
(ii) To prepare item-analysis chart. In this chart, at first, the serial number of items is written
in the columns.
(iii) After this, the answer-sheet of each student is taken and it is seen whether he has solved
it correctly or not, and a right tick mark is given for the right response and a cross mark
is given for the wrong response.
(iv) In each column of the chart from top to bottom, the right tick marks are counted and are
changed into percentage in order to write them in the form of difficulty index.
(v) To calculate discrimination index, we divide the analysis chart into almost three equal
parts from top to bottom.
(vi) Now, each item of the test in the chart is studied to see whether its difficulty index is
between 20-80 or 10-50 as per the objective of the test and whether its discrimination
index is above .3 or not.
• Using the information provided in you can compute the ‘Difficulty Index’ which is a
quantitative indicator with regards to the difficulty level of an individual item or question.
It can be calculated using the following formula :
• Difficulty Index

()
Number of Students with the Correct Answer R
= Total number of Students who Attempted the Question T
()
R 13
= = = 0.54
T 24
• The ratio of students’ group that solves a question correctly or knows it actually is called its
difficulty index. Difficulty index assists to arrange items in sequence, and indicates what
item will be placed first and what item will follow it or will come in the end.
• 50% Top and 50% Bottom Group Right Response Method
• For example, a subject teacher wants to prepare a weekly objective test containing 10 items.
He has Calculating Difficulty Index By Formula
• According to the formula method, the following formula is used to calculate difficulty level
of items :
• The ‘Discrimination Index’ is a basic measure which shows the extent to which a question
discriminates or differentiates between students in the ‘High Marks’ group and ‘Low Marks’
group. This index can be interpreted as an indication of the extent to which overall knowledge
of the content area or mastery of the skills is related to the response on an item.

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