2. Sample
In choosing the sample, the writer used purposive sampling technique. Purposive sampling is a technique that determined by certain considerations.
11
Some consideration used by the writer to choose the sample was based on the location of the place of the research which was accessible. It was really helpful for
writer to conduct the research as the writer could easily accessed the students and collected the data. Moreover, the consideration was also based on a
recommendation by the English teacher of MAN 19 Jakarta. Garfield, et al. stated that this sampling technique produces a sample where
the groups are selected according to specific characteristic that are considered to be important.
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The writer selected 54 students out of the population number which are class XI IPA and class XI Agama 1. The determination was based on
some consideration that these classes had same amount of students and the test result about narrative text that was distributed to population class showed that
both of the classes were homogeneous. So, the writer considered that students’
ability in reading and understanding narrative text were on the same level. According to Schutt, the size of the sample and the homogeneity of the population
affect the degree of error due to chance.
13
Therefore, the writer considered that the same amount of students in both of the classes was helpful to analyze the data.
Schutt added that the more homogeneous the population, the researchers can be more confident about the representativeness of a sample of any particular size.
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D. Instrument of the Research
The instrument of the research used in this study was a test. The test consisted of 40 questions of narrative text in the form of multiple choices. The test
were tested out to some students and the results were calculated and analyzed using ANATES software to find out the validity and reliability of the questions.
11
Sugiyono. op.cit., p. 124.
12
Richard Garfield, et al., Technical brief –Purposive sampling and site selection, Geneva:
ACAPS, 2011, p. 4.
13
Russell K. Schutt, Investigating the Social World: The Process and Practice of Research, 7th Edition, Thousand Oaks, CA: SAGE Publications, 2012, p. 158.
14
Ibid.
From the validity and reliability test, there were 25 significant questions of 40 questions. The writer then chose 20 questions based on some consideration to be
tested in experimental and control class as pretest and posttest.
E. Technique of Collecting Data
In order to get the data, the writer used tests and questionnaire as the technique of collecting data. The tests were divided into pretest and posttest.
Pretest was provided by the writer to find out students’ achievement in reading
narrative text before the research was conducted. The writer gave the treatment to one class and gave no treatment to another class. Then after four meetings of
treatment, the writer gave the posttest to both the classes. Posttest was performed to measure the acquisition of learning outcomes by the end of the treatment.
Afterward, the results of both the classes were compared by the writer. The questionnaire was conducted to gain the information about learning
narrative text using mind mapping technique in various aspects. There were 10 questions that were asked to the students about learning narrative text before and
after using mind mapping technique.
F. Technique of Data Analysis
Data analysis was the last procedure of the quasi experimental design used by the writer. In order to obtain the result of this study, the data was analyzed
using statistical analysis. The data on the pretest and posttest were collected, and analyzed with the SPSS 15.0 for Windows Evaluation Version program. To find
the final result of this study, several tests should be passed, such as normality test, homogeneity test, and hypothesis testing.
The purpose of normality test was to make sure that the data were normally distributed. The population of this study could be said as normal population
because they have received narrative text material at the first grade. And when the writer distributed a test about narrative text, they could pass it and succeed to
understand the test and answer the questions. Normality test is done with requirement as follows: If the significance score 0.05, so the data is come from
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