Population and Sample

C. Population and Sample

1. Population

Sugiyono (2011:80) defines population as generalization area that consist of object or subject of the research which has certain quality and characteristics that will

be learned by the researcher. Besides, Wirodikromo (2001:3) defines the population as all objects of a defined group that will be studied for collecting the information on data driven decision. Furthermore, Herhyanto, et al, (2014:1.10) confirm that population is covering all the members of the defined group as the target of the research. Hence, based on those statements, the researcher determined the population of the research.

The population of the research was the eighth grade of SMP Negeri 1 Ulugawo that consisted of three classes and of 91 students. The number of population can be seen at the following table below.

Table 2

The POPULATION CONDITION of the EIGHTH GRADE STUDENTS of SMP NEGERI 1 ULUGAWO in 2015/206

No.

Class

Number of Students

(Source: Administration Office of SMP Negeri 1 Ulugawo)

2. Sample

Sample can be defined as a part of all population that represent all the students’ characteristics. Sugiyono (2011:81) asserts that sample is a part of the total

amount and representative of characteristics of the population. Simply, Wirodikromo (2001:3) defines sample is part of population, while Herhyanto, et al., (2014:1.10) confirm that sample as amount of partly members of population. The existence of sample in research takes a very important role because basically it determines the quality of the researcher itself. The quality sample is a representative sample (Anggoro, et al., 2011:4.2).

In deciding samples of the research, the researcher used the cluster random sampling to their determination. As Anggoro, et all.. (2011:4.7) say that on cluster random sampling, the sample is not selected individually directly, but it is selected through random groups. Here are several procedures in selecting sample through cluster random sampling as follows.

a) Identify the research population. The research population was 91 students of the eighth grade of SMP Negeri 1 Ulugawo.

b) Identify the desired sample size. The desired sample size was 60 students which is considered as fulfillment of a

condition of the chosen of statistic parametric form. So the size of each sample should be even (≥30).

c) Identify and define the logical cluster. The logical cluster of the research is classroom.

d) List the entire cluster (or obtain list) that make up the population of clusters. The list of cluster can be seen on Table 2. The clusters consisted of six classes.

e) Estimate the average number of the population of clusters.

f) Determine the number of cluster needed by dividing the sample size by the estimated size of a cluster.

g) Select the numbers of cluster randomly. However, to make simple, the steps that had been done by the researcher as

follows.

a) The researcher made the lottery as many as the clusters of the research population then numbers each of them (3 lotteries).

b) The researcher asked a student from each cluster as the representation to take the lottery, one lottery for a student.

c) The researcher decided what the number that will be the research sample is.

d) The researcher made another lottery as much as three lotteries for decide the control group and experiment group.

e) The researcher asked a students to take a lottery that will be as the experiment group.

f) And then the researcher asked another student to take a lottery that will be as the control group.

Finally, the researcher had observed the both selected cluster, namely experiment class and control class. In conducting the research, the researcher gave treatment to the both class, in order that, the researcher taught the students of experiment class by using Modelled Writing and taught the students of control class through conventional teaching method. Here, the researcher set a purpose to compare which one is more effective the result of the students’ achievement between two classes, in which learning through Modelled Writing or without Modelled Writing.

Table 3

The TOTAL SAMPLE of the EIGHTH GRADE of SMP NEGERI 1 ULUGAWO in 2015/2016

No.

Class

Number of Students