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3. No correlation: indicates no relationship between the two variables. A
correlation coefficient of 0 indicates no correlation. In this research, the researcher examines the relationship between two
variables; one independent variable X and one dependent variable Y. 1
The independent variable predictor variable The vocabulary mastery of the eighth grade students of SMP Negeri 4
Wates. 2
The dependent variable criterion variable Reading comprehension of the eighth grade students of SMP Negeri 4
Wates Y. The relationship of the two variables can be shown as follows:
Figure.2.D iagram of the relationship between students’ vocabulary
mastery
X
and reading comprehension
Y
In which: X
: Students’ vocabulary mastery
Y : Students’ reading comprehension
: Correlates
X Y
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B. Setting
This research was carried out in SMP Negeri 4 Wates. It is located in Wates, Kulonprogo. The research was conducted on the eighth grade students
of SMP Negeri 4 Wates in the academic year of 20132014.
C. Population, Sample, and Sampling
1 Population
Population is the whole number of objects of the research, in which the sample is taken. In this study, the population to which the researcher carried
out was all the eighth grade students of SMP Negeri 4 Wates that consist of 5 classes.
2 Sample
Cooper and Schindler 2008:82 say that a sample is a part of the target population, carefully selected to represent that population. In this study, the
researcher took 28 students as the sample from whole population. 3
Sampling Sampling is the process of selecting units from a population so the sample
will represent the population and yet, by which the results can be generalized back to the population from which they were chosen Bungin:2006.There
were 5 classes in the population. In this study, the researcherintended to use cluster random sampling to get the sample. The researcher chose the class
randomly. Cluster random sampling is a way of selecting sample randomly based on the existing group. In this case, the researcher took one class among
five classes.
