1. Pre-Test Session
On February 12
th
, the researcher scheduled to enter Class XI I IPS which was a control class. The researcher gave the explanation about
writing essay using power point and an example of essay for about 30 minutes. Then, the students are given one hour to write their essay. It is the
pre-test for control class. On Februari 21
st
, the researcher scheduled to enter Class XI I IPA which was an experimental class. The researcher did the same way like she
did in control class. The students are asked to write their essay which they could choose their own topic as long as it was analytical text.
2. Post-Test Session
In the next meeting, on February 28
th
, the students in experimental class were explained about how to use mind mapping in writing essay.
They are asked to make an essay using mind mapping. It is the post test of the research.
And the last session, on March 5
th
, the researcher reentered to the control class in order to ask them writing their second essay without using
mind mapping treatment. The researcher only gave the wider explanation about how to write an essay easily. Then, they were asked to do the post
test. Therefore, the whole process of this resarch took two meetings in every class.
C. The Population and the Sample 1. The Population
The population of this study is the students at the Eleventh Grade in Senior High School of Muhammadiyah 25 Pamulang. The total number
of population is 142 persons which is divided into four classes, they are class XI IPA I, class XI IPA II, class XI IPS II, and class XI IPS II
2. The Sample
In selecting sample, non probability samplingis used as a technique of selecting the sample. Non probability sampling is based on the
consideration or subjective valuation; there is no use of probability theory in selecting the sample. In this case, convenience samplingas a kind of
non-probability sampling is used. Convenience sampling is a technique of selecting sample based on accidental reason, the populations of the
research are ready to be a sample or in another case, the sample is from the closest persons.
2
In this research, two classes are used; they are class XI IPA 1 and class XI IPS 1. Both of those two classes are categorized as progressive
class in their school and they are regarded as best-representation from their study program. The Class XI IPA 1 is taken as experimental group which
has been taught using the treatment of mind mapping technique and the Class XI IPS 1 as control group. The number of students in experimental
group is 29 persons and the control group is 29 persons. Therefore, the total number of students used as the sample of this research is 58 persons.
D. The Research Instrument
Sugiyono said that mostly the researchers in education arranged the research instrument by themselves. It happens because not every available
research instrument has already being tested or suitable with their research situation.
3
Considering this case, the written test is used as research instrument.
E. The Quality of Instrument
The written test need to be measured its validity and. reliability in determining the quality of the instrument.
1. Validity
2
SyofianSiregar, MM. StatsitikaDeskriptifuntukPenelitian, Jakarta: Raja GrafindoPersada, 2010 p.148
3
Prof. Dr. Sugiyono, MetodePenelitianPendidikan. Bandung: Alfabeta, 2009 p. 148
First element that is used to measure the test is validity. There are many types of validity such as content validity, construct validity, and
criterion validity.
4
The type of validity that is used in this research is construct validity. To examine the construct validity, the judgment
experts is used. In this case, the researcher has already consulted the test with her advisor and an English teacher at school where she did
the research. 2. Reliability
The second element is reliability. Reliability refers to the extent to which test scores are free of measurement errors.
5
In this research, the analytic scoring is used. The analytic scoring is one of many types of
rating scales in measuring writing. “In analytic scoring, scripts are rated on several aspects of writing or criteria rather than given a single
score.”
6
F. The Technique of Data Collecting
Written test is the only one technique that used by the researcher in this research. Giving the explanation about writing essay to both of classes,
the experimental and the control class, is the first step that the researcher do to collect the data. Then they were asked to write an essay.
The test which is the only instrument of this research was about writing analytical text using essay form. The students were asked to write
everything which they interesting about and make the analytical reason of it. It was also considered from the current material which is studied by all of
them in their English language subject. The scoring of the test is focused on their ability in using mind
mapping and how they generate ideas from general one to the details. Other
4
Muijs, Op.,cit., p. 66
5
Ibid., p.71
6
Sara Cushing Weigle, Assessing Writing. New York: Cambridge University Press, 2002, p.114
