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CHAPTER IV DATA ANALYSIS
In this chapter, there are five important analyses that would be discussed. They are the analysis of the try out, the analysis of cycle 1, the analysis of cycle 2,
the analysis of students’ achievement and analysis of questionnaire.
4.1. Analysis of the Try Out
4.1.1. Validity In this study the writer used the Pearson Product Moment formula to
analyze the validity of each item. In this study there were two try out test conducted, that is for the pre test item and post test item. It is because the item test
for the pre test and post test were different. For the items of pre test, it was obtained that from 40 items there were 33
items which were valid and 9 items which were invalid. While for the post test items, it was obtained that from 35 items there were 32 items which were valid
and 3 items which were invalid. The items were said to be invalid if the computation result of the r
xy
value the correlation of score each item was lower than r
table
value. From those results the writer decided to use 30 item test, both for the pre
test and the post test. The example of computation item validity and the list of the validity of each item can be seen in appendix.
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4.1.2. Reliability The formula used by the writer to calculate the reliability of her test is the
formula of Kuder Richardson 21 K-R 21. Before computing the reliability, the writer had to compute the Variant Standard Deviation and the mean of the scores
M first. After finding the Variant Vt and the mean of the scores M, the writer could compute the reliability of the test.
From the computation the reliability test of the pre test, it was found that the calculating of r
11
was 0.920. The test item is reliable if r
11
is higher than r
table
. For α = 5, the number of subjects = 30, then the critical value for r
table
= 0.361. While from the computation the reliability test of the post test, it was
found that the calculating of r
11
was 0.899. For α = 5, the number of subjects = 30, then the critical value for r
table
= 0.361. Thus it can be concluded that the test item both for the pre test and the post
test used in this research is reliable since the computation of the instrument of reliability r
11
was higher than the critical value for r
table
. The computation of each reliability of the test can be seen in appendix.
4.1.3. Discriminating Power The Discriminating power have 5 classifications, it was to know the level
of DP of each item. The classifications were very poor, poor, satisfactory, good, and excellent.
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After calculating all items for the pre test, it was found that 2 items considered as a poor item. For items considered as good items were 8 items. And
for the rest 25 items were considered as satisfactory items. While for the post test result, it was found that 7 items belong to a poor
item. For items considered as good items were 6 items, 26 items belong to satisfactory items and 1 item considered as an excellent item.
The writer did not use the items that belong to poor item. For the complete result of DL could be seen in appendixes.
4.1.4. Difficulty Level The difficulty level of an item is to shows how an easy or difficult the
particular item proved in the test. There are three classifications of the index of difficulty; those are difficult, medium and easy.
After calculating all items for the pre test, it was found that 13 items considered as easy items. For items considered as medium items were 18 items.
And for the rest 4 item were considered as difficult item items. While for the post test result, it was found that 18 items belong to easy
items. For items considered as medium items were 17 items and 5 item considered as difficult items.
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4.2. Analysis of Cycle 1
Kategori