E. Research Instrument
The writer uses pre-test and post-test as the research instruments to collect the data. It was consist of 25 numbers of vocabulary test which consists of 15 numbers
of multiple choice questions and 10 word matching task in every pre-test and post- test. The test was used in order to know the different achievement between the
experimental class and controlled class after the treatment. Before the test was given to the students, the writer has already measured the validity and reliability of the test.
Validity is “the process of collecting and analyzing evidence to support such inferences.”
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Validation in language testing is needed to ensure the defensibility and fairness of interpretations based on test performance.
According to Frankael , “reliability refer to the consistency of the scores
obtained —how consistent they are for each individual from one administration of an
instrument to another and from one set of items to another .”
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In this research, the writer measures the validity and reliability of the research instrument by using
ANATES V.4. F.
Data Analysis Technique
In this study, the writer used T-test to find out the differences between students’
score which are taken from pre-test and post-test in experimental class and controlled class. Before calculated the T-test, the writer measured normality and homogeneity test, first.
Moreover, the writer used SPSS v.18 for Windows software to analyze normality test and homogeneity test.
1. Testing Requirement
a Normality Test
Normality test was done on two classes; those are experimental class and
5
Frankael, Loc.Cit, p. 148
6
Ibid., p. 154
controlled class. Normality test was used to know whether the data from both sample groups which examined come from the population of normal distribution or not.
The writer uses SPSS v.18 for Windows to do normality test which is Analyze- Descriptive Statistic-Explore-Plots-Normality Plots with Tests, the steps as follows:
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1 From the menu at the top of the screen click on Analyze then Descriptive
then Explore. 2
Move all of the data into the Dependent list 3
Under Display ensure that there is only a tick next to Plots. 4
Click on the Plots tab to open the plots dialogue box. 5
Under Boxplots click None, and remove any ticks under Descriptive. Place a tick in Normality plots with tests. Under Spread vs. Level tick none.
6 Click Continue, and then OK.
b Homogeneity Test
Homogeneity test is conducted after getting the data that distributed normally from the normality test. It was used to know the similarity of the two conditions or
population. If the significant value ρ 0.05, it means that the population has similarity.
The writer uses SPSS v.18 for Windows to do homogeneity test which is Analyze- Compare Means- One Way ANOVA- Option- Homogeneity of Variance, the
steps as follows: 1
From the menu at the top of the screen click on Analyze then Compare Means then One-Way ANOVA
2 Move the data from experimental class into the Dependent list and the data
from control class into the Factor 3
Under Contrast and Post-Hoc ensure that there is a tick next to Options.
7
Andrew Garth, Analysis Data Using SPSS A practical guide for those unfortunate enough to have to actually do it, USA: Sheffield Hallam University, 2008, p. 73
4 Click on the Options tab to open the options dialogue box.
5 Place a tick in Homogeneity of variance tests.
6 Click Continue, and then OK.
G. Hypothesis Test
For hypothesis test, the writer uses t-test to find out whether there is significant difference between experimental class and control class in this study. The writer uses
t-test which is adapted by Anas Sudijono to find the result. There are several steps before applying the t-test formula.
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The formula of t-test which is used in this research is:
Explanation:
t
o
=
the value of „t’ count M
1
= Mean variable of experimental class M
2
= Mean variable of controlled class SE
M1
= Standard error of experimental class SE
M2
= Standard error of controlled class
The procedures used are as follow: 1.
Determining Mean Variable X: M
1
= 2.
Determining Mean Variable Y: M
2
=
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Anas Sudijono, Pengantar Statistik Pendidikan, Jakarta: PT Raja Grafindo Persada, 2004, pp. 314-316.
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