C. The Population and Sampling Technique of the Research
1. Research Population
The population in this research is from all first year of students in MTs. Muhammadiyah 1 Ciputat, there are three classes: VII-1, VII-2, and VII-
3. The amount of the students of seventh grade in this school is 96
students.
2. Sampling Technique
In this study,the researcher usedPurposive Sampling. The researcher took the sample from the judgment that was representative of the population or
includes subjects with needed characteristics. In this study, the researcher took the sample by interviewing the English teacher in order to know
which classes that have the same ability in English lesson, had same facilities, on the same level and also give the pre-test for all classes to
know the class that had same score. Two classes that had choosen become controlled and experimental class. Finally, the samples of this research
were; class VII-1 as the experimental class and VII-2 as the controlled class.
D. Instrument of the Study
The instrument consists of 35 multiple choices given for experimental and controlled class. Meanwhile, the instrument made based on syllabus and took
from English text book.
E. Technique of Collecting Data
To collect the data, the researcher used a multiple choicetest as the primary instrument. There are two types of tests; pretest and posttest. The pre-test was
given in experimental and controlled class to know how far the students‟
vocabulary understanding before receiving treatment. The post-test was given to
know their vocabulary understanding after the treatment. Before the researcher given the pre-test, the reseacher analyzed the instrument to know whether the
instrument used in this study is valid and reliable before being used to collect data.
F. Technique of Analyzing Data
1. Validity
Validity is one of important requirements of evaluation to know whether the test is valid. A test is said to be valid if it measure accurately what it is
intended to measure.Before administering the pre-test, the writer will analyzed the validity and reliability of pre-test in order to find out
whether the test is valid or good to be used. The writer will use software ANATEST version 4.0.9 developed by Drs. Karno To, M.Pd. and Yudi
Wibisono, ST. The criterion of validity:
r
xx
= 0,91 – 1,00 = very high
r
xx
= 0,71 – 0,90 = high
r
xx
= 0,41 – 0,70 = enough
r
xx
= 0,21 – 0,40 = low
r
xx
= 0,21 = very low
2. Reliability
Realibity is whether an instrument can measure something to be measured constantly. To know the reliability of the instrument used to collect data,
the writer used “ANATEST” software version version 4.0.9 developed by Drs. Karno To, M.Pd. and Yudi Wibisono, ST.
.
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