According to Heaton, “Facility values and the discrimination indices are usually recorded together in tabular form and calculated by similar procedures.”
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Above all, by analyzing the test items in term difficulty level and discriminating power, the teacher will know the qualities of the test items whether the
test items have an easy, moderate, or difficult level and a high or low discriminating power.
To calculate them, it can use the formula as follows:
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In which: FV
: The index of difficulty R
: The number of correct answers N
: The number of students taking the test D
: Discriminating index U
: Upper half L
: Lower half n
: Number of candidates in one group
52
J.B Heaton, op. cit., p. 182.
53
Ibid.
FV =
or FV =
D =
An additional, difficulty has a bearing on the discrimination value of a test –
that a test which is too hard or too easy will not discriminate between individuals of different levels of achievement as well as one which is more appropriate for the range
of abilities in the group.
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4. The Importance of Item Analysis
Talking about the importance of the item analysis, it is very important for the teacher to get much information from the result of the analyzing the items. By the
analyzing, the teacher will know about the achievement of his or her teaching and learning process in the classroom. Not only the process itself but also the teacher
knows the students’ performances. It means that, there are so many benefits of the
item analysis.
Based on Anthony J. Nitko, there are six points of the importance of item analysis, those are:
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1. “Determining whether an item functions as the teacher intends.” In
this book, there are five points about deciding the functioning items which teacher needs to consider: a whether it seems to be testing the intended
instructional objective, b whether it is of the appropriate level of difficulty, c whether it is able to distinguish those who have command of the learning
objectives from those who do not, d whether the keyed answer is correct; and e for response-choice items whether the distractors are functioning.
2. “Feedback to students about their performance and as a basis for class
di scussion.” The teacher gets information about the performance of their
students. For example in reviewing the test, the teacher will know the students’ errors.
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Victor H. Noll, Introduction to Educational Measurement, Boston: Houghton Mifflin Company, 1965, p. 180.
55
Anthony J. Nitko, op. cit., p. 284-286.
