The Method of the Research
43 Here is the distribution of the questions‟ type:
No Type
Question Items
1. Simple past tense irregular verbs
1-7, 9-16, 18, 2.
Simple past tenseregular verb 8,17, 19-20,
Next, to know the validity of test items, the writer uses discriminating power and the difficulty item. The use of discriminating
power of the tests item is to know the difference response between the proportions of the high and low groups to the item.
51
The following is the formula to calculate the discriminating power:
52
D = The index of Discriminating power. U = The number of pupils in the upper group who answered the item
correctly. L = The number of pupils in the lower group who answered the item
correctly. N = Number of pupils in each group.
Then, the discriminating scale uses:
53
DP Remark
0.6 – 1.0
Very good 0.4
– 0.6 Good
51
Kathleen M. Bailey, Learning about Language Assessment: Dilemmas, Decisions, and Direction, London: Heinle Heinle Publisher, 1998, p.135
52
Wilmar Tambunan, Evaluation of Student Achievement, Jakarta: Depdiknas, 1998, p.139
53
J. B. Heaton, Classroom Testing, New York: Longman Inc, 1990, p. 174
D = U-L N
44 0.1
– 0.3 Ok
-1 – 0.0
Bad
Furthermore, the difficulty item analysis concerns with the proportion of comparing students who answered correctly with all students
who follow the test. To know the difficulty item of the test, the following formula is used:
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P = Index of difficulty. R = Total number of students who selected the correct answer.
T = Total number of students including upper and lower group
The following is the criterion of index difficulty:
55
ID Remark
– 0.30 High
0.30 – 0.79
Medium 0.80
– 1.00 Low