C. Population and Sample of the Research
1. Population
Population is all cases, situation, or individuals who share one characteristic.
5
The population of this study is 373 tenth grade students of SMAN 1 Kota Tangerang Selatan which are divided into 10 classes start from X MIA 1-X MIA 6
and X IIS 1-X IIS 4.
2. Sample
Sample is a subset of individuals from within population.
6
Sample is a part of population that is supposed to represent th
e population’s characteristics. The technique sampling which was used in this research is purposive sampling
technique since the writer chose the sample for the specific purpose. Purposive sampling technique is a technique which selects the sample based on the purpose
of the research.
7
The purpose of this research is to help students who got low score to get better reading comprehension.
The sample of this research is 86 students of tenth grade from two classes; X MIA 3 and X MIA 4. X MIA 3 consists of 43 students and X MIA 4 consists of
43 students. Between the two classes, the class which got lower score in pre-test will be an experimental class. Treatment was given in that class. The class which
got the higher one as a control class since it was difficult to find the class which has same achievement. Based on the pre-test score, X MIA 3 was chosen as
experimental class and X MIA 4 as control class.
D. Calibration of the Instrument
The main instrument used in this research is test. Before applying the instrument to sample of the research, the test was tested to other students in the
same grade except students as the sample of this research. This step is needed to see the validity, reliability, discriminating power, and item difficulty of the
5
Ibid., p. 231.
6
Ibid., p. 232.
7
Louis Cohen, et al., Research Method in Education, 6
th
Ed., New York: Routledge, 2007, p. 115.
instrument before it is applied to the sample of this research. The writer made test consist of 50 numbers in type of multiple choice. The writer tested the instrument
to the students in the same school but not to students as the sample. In this case, X MIA 3 and X MIA 4 were choosen as sample of the research while the test was
tested to X MIA 2 class of SMAN 1 Kota Tangerang Selatan. The writer applies four steps to analyze the examined test item. They are:
1. Validity
Validity is important to know whether the test is valid or not. According to Arikunto, a test is valid if it measures what it purposes to measure.
8
To test the validity of the instrument, the writer
used “ANATEST” software version 4.0.9 developed by Drs. Karno To, M.Pd. and Yudi Wibisono, ST. After the calculation
using “ANATEST”, the writer found from 50 questions that were given, there are 19 questions which are valid and then the writer revised 6 questions to make it
became 25 questions.
2. Reliability
Reliability is whether an instrument produced consistent result. According to Arikunto, test is reliable if it provides consistent and stable characteristic.
9
To find out the realiability of the instrument
, the writer used “ANATEST” software version 4.0.9 developed by Drs. Karno To, M.Pd. and Yudi Wibisono, ST.
The criterion of reliability:
10
= 0,91 – 1,00 = very high
= 0,71 – 0,90 = high
= 0,41 – 0,70 = enough
= 0,21 – 0,40 = low
= 0,21 = very low
8
Suharsimi Arikunto, Dasar-Dasar Evaluasi Pendidikan, Jakarta: Bumi Aksara, 2003, p. 65.
9
Ibid., p. 89.
10
Ibid., p. 102.
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