The Population and Sample

C. The Population and Sample

1. Population

According to Dowdy, et al (2004:25) , ―A population is usually known to be

a natural, geographical, or political collection of people, animals, plants, or objects .‖ Ary says, ―Population is all members of well-defined class of people, events, or

object‖. On the other hand, the researcher has to determine the population from people, events, or object based on the research.

The population of the research is the eighth grade of SMP Negeri 1 Hiliserangkai that consists of 174 students. The number of population can be seen at the following table.

Table 2

THE POPULATION of the EIGHTH GRADE STUDENTS of SMP NEGERI 1 HILISERANGKAI

No

Class

Total of the students

Source: Office of SMP Negeri 1 Hiliserangkai

2. Sample

Sample is a part of population that can represent the characteristic of population. Sprinthall and friends (1990:28) state, ―A sample is a smaller number of observations taken from the total number making up a given population. So, the sample is a small proportion of a population selected for analysis.

To take the sample in the research, the researcher uses Cluster Sampling Technique. As Khotary (2004:55) says that the researcher must prepare a sample design for her study, plan how a sample should be selected and of what size such as a sample would be. So, the researcher must determine the number of cluster to be selected and select it randomly. This is chosen by the researcher as her design of sampling because considering the policy of the school and the similarity of the students’ ability in studying as she found from that school.

However, in the research, the researcher takes the sample at the eighth grade of SMP Negeri 1 Hiliserangkai. The sample chosen is not individual but a class who are naturally together. In addition, Ary (2002:168) says that once a cluster is selected, all the members must be included in the sample.

According to Gay (2000:130), there are some steps to select the research sample in Cluster sampling as follows:

a. Identify and define the population. The research population is 174 students at the eighth grade of SMP Negeri 1 Hiliserangkai in 2015/2016.

b. Determine the desired sample size. The desired sample size is 68 students. It is considered of fulfillment of one of the conditions of the chosen of statistic parametric form. So the size of the sample should be even (≥ 34).

c. Identify and define a logical cluster.

A logical cluster is classrooms.

d. List the entire cluster (or obtain list) that make up the population of clusters. There are three classrooms. For more clearly the list of entire cluster can be seen in Table 3.

e. Estimate the average number of the population members per clusters.

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

g. Randomly the select needed number of cluster. Therefore 2 of the 3 classrooms are randomly selected by assigning a number to each classroom. Based on the Table 3, there are 3 classrooms that consist of 34 students (VII-1, VII-4, and VII-5), while in the research the researcher needs two classes as sample. In deciding the sample from those classes, the researcher uses lottery. The steps that are be done by the researcher are as follows:

1) The researcher makes the lottery as many as the classroom and numbering it 1 to 3.

2) The researcher asks the representation from each class to take the lottery. One representation takes one lottery.

3) The researcher decides what the numbers that are Experimental Group and Control Group. For instance, the researcher chooses the number 1 is as Experimental Group and number 2 is as Control Group, so the classroom which gets number 1 as the Experimental Group and Number 2 as the Control Group. Then, the researcher holds the treatment to the experimental group by conduct Word Chain Game and in control group the researcher uses Real Teaching. After that, the researcher administers the post-test to the both groups.

h. Include in your study entire population members in each selected cluster. All the students in each of the 2 classrooms are in the sample (2 classrooms, 68 students per classroom on the average, equals the desired sample size). The sample of the research can be seen in the following table:

Table 3

THE TOTAL SAMPLE of the EIGHTH GRADE of SMP NEGERI 1 HILISERANGKAI

No. Class

Groups

Number of students

1 VIII-1

Experimental group

34 students

2 VIII-5

Control group

Source: Office administration of SMP Negeri 1 Hiliserangkai