F. Technique of Data Analysis
1. Calibrating the Instrument
To see the validity and reliability of the instrument, the writer conducted a test to another class with the same grade as the sample in
order to find out the validity, reliability, and difficulty of the questions before it was given to the students, which then the valid and reliable
questions were chosen to be the questions for pre-test and post-test, this test regarded as a pilot study. The writer conducted the pilot study for two
times; before pre-test and before post-test. Total population of this study consisted of 427 10
th
grade students of SMAN 7 Tangerang Selatan. In this case, X IPA 2 and X IPA 4 were chosen as the sample of this research,
therefore, the pilot test was taken beyond the sample class; it turned out that X IPA 5 was chosen to be the object of pilot study before pre-test was
given to the sample, and X IPA 6 was chosen to be the object of pilot study before post-test was given to the sample. Each questions of pilot test
consisted of 40 multiple choice questions, thus the total questions for pilot test was 80. The steps are described as follows:
a. Validity
According to Arikunto, a condition where the instrument can measure what it purposes to measure is called as validity.
11
A test is valid if it gives the corresponding information and can be used to reach
its purpose.
12
Therefore, testing the validity of the instrument is important since it is aimed to see whether the test is valid or invalid.
The “ANATEST” software version 4.0.9 which developed by Drs. Karno To, M.Pd and Yudi Wibisosno, ST. was used by the writer to
test the validity of the instrument. The result of the calculation of the first pilot test showed that from 40 questions, there were 21 questions
are valid and 19 questions were invalid. Meanwhile, the result of the
11
Suharsimi Arikunto, Manajemen Penelitian, Jakarta: Rineka Cipta, 2007, p. 167.
12
Zainal Arifin, Evaluasi Pembelajaran, Bandung: PT. Remaja Rosdakarya, 2009, p. 247.
calculation of the second pilot test showed that from 40 questions, there were 30 questions are valid and 10 questions were invalid
b. Reliability
According to Arifin, reliability is a scale to calculate the instrument consistency.
13
A test is reliable if it provides consistent and stable result.
14
Therefore, it is important to test the reliability of the instrument to see whether the instrument produces consistent result.
Just like testing the validity of the instrumen t, “ANATEST” software
version 4.0.9 which developed by Drs. Karno To, M.Pd and Yudi Wibisosno, ST. was used by the writer to test the validity of the
instrument was also used to test the reliability of the instrument. According to Sudijono, there are some criterions for considering the
item to be reliable;
If the is 0,70 or more, than the test is categorized into high
reliability If the
less than 0,70, than the test is less reliable or unreliable.
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Based on the criterion of reliability above, it turned out that the first pilot test got 0,77 score of reliability, and the second pilot test got
0,79 score of reliability. It means the both item of the test were reliable and categorized into high reliability.
2. Trustworthiness of the Research
Analyzing the normality and homogeneity of the data was done before measuring the hypothesis in order to prove that the research is trustworthy.
13
Ibid., p. 258
14
Anas Sudijono, Pengantar Evaluasi Pendidikan, Jakarta: PT Raja Grafindo Persada, 2011, p. 95.
15
Ibid., p. 209.
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