Table 3.1 Nonequivalent comparison group design
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Where: : Pretest of both experimental and control class.
: Posttest of both experimental and control class. X: Implementation of teaching narrative text using mind mapping technique.
C. Population and Sample of the Research
1. Population
The population of this study was the second grade students of MAN 19 Jakarta. It consists of 144 students divided into 5 classes
—IPA, IPS I, IPS II, Agama I, and Agama II. The population number is shown in a table below:
Table 3.2 Population
Class IPA
IPS I IPS II
Agama I Agama II
Number of Students
27 31
31 27
28 144
10
Christensen, op. cit., p. 332.
Pre-response measure
Treatment Post-response
measure Difference
Experimental class
X -
Compare Control class
-
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.
12
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.
14
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.