The Population and Sample of the Research
C. The Population and Sample of the Research
1. Population
Gay (2000:140) states, “Population is the group to which a researcher would like the result of study to be generalizable.” This the population of this research is the Students of SMP Negeri 3 Idanogawo in 2015/2016 which consist of 91 students divided in two classes.
Table 2 NUMBER OF STUDENTS
91 Students Source : office of SMP Negeri 3 Idanogawo
2. Sample According to Yount, 2006, population and sampling (online),
Sampling is the process of selecting a group of subjects for a study in sudh a way that the individuals represent the larger group from which they were selected. This representative portion of a population is called a sample.
It means that the sampling is the process of selecting a group of subjects that searched, while sample is the representative portion of a population that searched. There are many types of sampling that can be used by the researcher to select the sample. One of them is Cluste r Sampling. As Gay (2000:129) says, “Cluster Sampling randomly selects groups, not individuals. All the members of selected groups have similar characteristic.”
Related to the previous explanation, it is impossible for the researcher to randomly assign individual participants to groups, so she involves random assignment
of intact groups to treatment, not individuals. That’s why the researcher uses Cluster Sampling as the type of sampling to select the sample. As Gay’s opinion above, the sampling randomly select groups, not individuals.
Based on the information from the headmaster at SMP Negeri 3 Idanogawo, the researcher found that the classroom in the school consist of the students that have been assigned in a good order. They are grouped without consideration the level of the students’ ability. In addition, the English teachers in the school give the information that the students in every class have similar characteristic each other in teaching and learning process. It means, the researcher can randomly select the classrooms to groups as the sample.
According to Gay (2000:130), there are some steps to select the research sample in Clustering Sampling as follows:
a. Identify and define the population. The research population is 91 students at the eighth grade of SMP Negeri 3 Idanogawo in 2015/2016.
b. Determine the desired sample size. The desired sample size is 60 students. It is considered because the students
practice the conversation in pairs, so the sample size should be even.
c. Identify and define a logical cluster.
A logical cluster is classrooms.
d. List all cluster (or obtain list) that make up the population of clusters.
There are 3 classrooms. For more clearly the list all cluster can seen in table 3.
e. Estimate the average number of population members per clusters. The
members per cluster=
f. Determine the number of cluster needed by dividing the sample size by the estimated size of a cluster.
The number of cluster needed =
30 =2 classrooms
g. Randomly select the needed number of clusters. Therefore, 2 of the 3 classrooms are randomly selected by assigning a number to each classroom. Based on Table 2, there are 2 classrooms consist of 30 students (VII-1 and VII-2). There are many ways that can be used by the researcher to randomly select two classroom that will be as the sample. The easy one is taking lottery. The steps that will be done by the researcher as follows:
The researcher made lottery as many the classrooms. There are 3 classrooms, so the researcher will make the numberization in the lottery from 1 to 3.
The researcher asked the representations from each classroom to take the lottery. One representation takes on lottery.
The researcher decided what the number that would be the research sample is.
h. Include in your study all population members in each selected cluster. All the students in each of the 3 classroom were in the sample (2 classroom, 60
students per classroom on average, equals the desired sample size).