III. RESEARCH METHOD
This chapter is concerned with research design, population and sample, variables, data collecting techniques, research procedures, criteria of good test, result of the
tryout test, data analysis and hypothesis testing.
3.1. Research Design
This research is quantitative study using one group pretest-posttest design. The design used one class only as the experimental class. This class was given
treatment through STAD technique. This class had pretest, posttest and three times treatments. The pretest is used to find out the students’ preliminary ability
and the posttest is used to look how far the increase of the students’ vocabulary achievements after the treatments. The aim of this research is to investigate
whether there is any increase of students’ vocabulary achievement after being taught using STAD technique. The design is presented as follows:
TI X
T2 T1
: Pretest X
: Treatment T2
: Posttest Hatch and Farhady, 1982
3.2. Population and Sample
1. Population
The populations in this research was all the second year students at SMP Muhammadiyah 3 Bandar Lampung in academic year 2015-2016.
2. Sample
The researcher selects one class as the sample of the research by using random sampling technique which was using lottery and the result was class
VIIIE as the experimental class.
3.3. Variables
The research consists of the following variables: 1.
Students’ vocabulary achievement is dependent variable Y. It means the achievement of student’s vocabulary partly depends on their ability in
memorizing and understanding a number of English words in language. 2.
STAD technique is independent variable X. It means that STAD will influence the dependent variable in this case is students’ vocabulary
achievement.
3.4. Data Collecting Technique
In order to collect the data, the researcher use the following steps: 1.
Administering pretest The pretest was conducted to know how far the students have mastered the
vocabulary. The number of item in the test was 30 items. The pretest was administered once.
Kategori