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.
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A test is valid if it gives the corresponding information and can be used to reach
its purpose.
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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
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Suharsimi Arikunto, Manajemen Penelitian, Jakarta: Rineka Cipta, 2007, p. 167.
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Zainal Arifin, Evaluasi Pembelajaran, Bandung: PT. Remaja Rosdakarya, 2009, p. 247.
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