04 : Post-test for the control group
X : Treatment using audio visual aid
Y : Treatment using conventional teaching technique
In the design above, the subject of the research was assigned to the experimental group top line and the control group bottom line. First, the
quality of the subject was checked by giving them pretest 01 and 03, then the experimental treatment was performed to the experimental group, while the
control group was taught using conventional teaching technique. Then post test was conducted to both groups and then the results were computed statistically.
This method is simply called pretest posttest equivalent groups.
3.2 Population and Sample
The descroption of the population, sample, as well as sampling technique are as follows:
3.2.1 Population
Margono 2003:18 defines population as a complete set of individuals or subjects having common observable characteristics. In addition, Saleh 2001: 17, argues
that population is a group of people, object, items, or phenomenon, a group which the researcher would like the results of the study to be generalized, a group from
which information is collected. In quantitative research, the researcher attempts to discover something
about a large number of groups of individuals by studying a much smaller group. The group that they wish to learn is called population.
The population used to conduct the observation in this study was the students of grade eight of SMP N 1 Randublatung in the academic year of 2010
2011.
3.2.2 Sample
Sample is a representative of population which acts for the population and reflect the condition of population. According to Gall M.D 2003: 167, sampling refers
to this process of selecting a sample from a defined population with the intent that the sample accurately represents that population. This process refers to the
quantitative research. Therefore, in order to know the effectiveness of the topic, taking two classes had been done.
In grouping the subjects, I used purposive sampling. It is the one which is the person who is selecting the sample is who tries to make the sample
representative, depending on his opinion or purpose, thus being the representative subjective. That was by picking a group with the same background knowledge
level of the topic given. Then I decided class VIIIA as the experimental group and VIIID as the control group. Comparing their result of speaking of interpersonal
and transactional conversation where one class used audio visual aid and the other one did not use it was the next step. The first group was the experimental group
and the second one was the control group.
3.3 Research Variable
