CHAPTER IV RESULT OF STUDY
This chapter presents the result of the research, including the result of try- out, pre-test, and post-test, normality of pre-test and post-test data, the difference
between two means of pre-test and post-test, test of significance, and the discussion of the result.
4.1 The Result of Try Out
The result of try out was analyzed based on item validity, level of difficulty, discriminating power, and reliability. Those aspects influenced the
number of items that were used in the pre-test and post-test. Therefore, those aspects were very important to calculate.
4.1.1 Item Validity
Concerning with validity, Heaton 1979: 152 proposes that the validity of a test is the extent to which it measures what it supposed to measure. In this
research, the writer used the item validity and calculated them by using Point Biserial Correlation.
For example, the validity index of number 1 is 0.40. Then the writer consulted the table of r with N = 40 and significance level 5 is 0.312. Since the
result of the computation is higher than r in the table, the index validity of item number 1 is considered to be valid. See Appendix 4
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Based on the computation of all items, there were 9 items which were invalid on the try-out test. Those were the item number 3, 8, 14, 20, 24, 27, 32, 35,
and 38. In these items, based on the calculation done after the try out test, it was found that r
pbis
r
table
. Since there were 31 valid items, the writer only used 30 items for the test based on consideration of time allocation and calculation.
4.1.2 Level of Difficulty
Level of difficulty is calculated from the number of students who answered correctly and the total number of the students. After calculating the item
number 1 for example, the index of difficulty level is 0.28. According to the criteria, the difficulty level of item number 1 is difficult. The index of other items
can be seen in Appendix 5. As mentioned in the previous chapter, there are three categories for level
of difficulty. They are difficult, medium, and easy. After calculating 40 items of try-out test, there were 20 items that were easy, 15 items were medium, and 5
items were difficult.
4.1.3 Discriminating Power
Discriminating power is calculated from the number of students in the upper and lower group who answered correctly and the number of all students in
the upper and lower group. After calculating the item number 1, the discriminating power of it is 0.45. Therefore the criterion of the item number 1 is
good. See Appendix 6 for the other result
In discriminating power, there are four categories. They are poor, satisfactory, good, and excellent. From 40 items of try-out test, there were 10
items that were poor, 28 items were satisfactory, and 2 items were good.
4.1.4 Reliability
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