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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.
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D. Data Collections Techniques
Before analyzing the data, the researcher collects the data. The main components of the technique of collecting the data are follows:
1. Research Instruments
a. The test of Vocabulary Mastery
The test of vocabulary mastery is intended to collect the data about students’ vocabulary mastery. The test is an objective test in the form of
multiple-choice.There were 45 items of questions. The blueprint and the objectives test of vocabulary can be seen at Appendices 3 and 4.
The final score is calculated:
b. The test of Reading Comprehension
The test of reading comprehension is intended to collect the data about the students’ reading comprehension. The test is an objective test in the form of
multiple-choice type. There are four alternatives in each item.There were 50 items of question. The blueprint and the objective test of reading
comprehension can be seen at Appendices 6 and 7. The final score is calculated:
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2. Data validity and reliability
An instrument can be said to be a good one if it is valid and reliable. Before the instruments are used, they have to be tried out. It is intended to
find out the validity and reliability of the instruments.
a. Validity
An instrument can be valid if it can reflect what is being measured Arikunto, 2002:145. Cooper and Schindler 2003:231 say that validity
refers to the extent to which a test measures what we actually wish to measure.
In this study, to verify the item validity of instrument, each item of the test is correlated with the total score by using Point Biserial Correlation formula.
The item of the test is considered valid if the result of the correlation coefficients r
xy
is as many as the r table of product moment. The number of students joining the try out is 28, with the significance level
α = 0.05 the r table is 0.374
.
The item of the test is considered not valid if the correlation coefficient is lower than r table.
The criterion is as follows. r
o
r table = valid r
o
r table = invalid Budiyono, 2000:69
The results of the try out: 1
From 45 items of the test of vocabulary mastery, 25 items are valid and 20 items are not valid.
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