26
In analyzed the test item, the researcher uses to ways to know the trustworthiness of the data follow:
1. Discrimination Power The analysis of discriminating power test items is to know the
performance of the test through distinguishing students who have high achievement and low achievement. Discriminating power provides more detailed
analysis of the test items than the item difficulty, because it shows how the top score and lower score performed on each item.
8
The computing of discriminating power uses the formula following:
9
D = U-L N
In which, D
: The index of discriminating power U
: The number of pupils in upper group who answered the item correctly
L : The number of pupils group who answered item
Correctly N
: Number of pupils in each group Next, the discriminating power scale uses:
Table 3.2 The classification of Discriminating Power
DL REMARKS
0.6- 10 Very Good
0.4-0.6 Good
0.1-0.3 Ok
-1-0.0 Bad
8
Kathleen M. Bailey, Learning about Language Assessment: Dillemas, Decissions, and Direction London:Heinle Heinle Publisher, 1998, p. 135.
9
Tambunan Willmar, Evaluation of Students Achievement, Jakarta:Depdiknas, 1998, p. 139.
27
2. Difficulty Items The researcher analyzes the students’ test. It categorized into high,
medium, and low. In this study the researcher compares the difficulty items analysis by comparing students who answer correctly with all of students who
follow the data. The formula which is used is:
Table 3.3 The Classification of Difficulty Level
DL REMARK
0-0.30 High
0.30-0.79 Medium
0.80-1.00 Low
L. Validity of the Test
“Validity is a measurement instrument which shown whether the instrument valid or not”.
10
It means that validity is one of the crucial conditions in implementing a research including Classroom Action Research CAR. By using
the validity, there should be no irrelevant point of misleading in reflecting the data. The researcher uses the Anates to get the validity of the instruments before
implementing the test. The test result of pre test instrument shows that the mean was 20.52, the
correlation was 0.53 and the reliability of the test was 0.70. The test result of post test 1 instrument shows that the mean was 19.61, the correlation was 0.55 and the
reliability of the test was 0.71. The test results of post test 2 instrument shows that the mean was 23.61, the correlation was 0.57 and the reliability test was 0.72.
10
Suharsimi Arikunto, Prosedur penelitian Suatu Pendekatan Praktek, PT Rineka Cipta:Jakarta, 2002, p. 144.
28
CHAPTER IV RESEARCH FINDINGS AND INTERPRETATION
This chapter presents the finding of research. In this case the way to develop students’ vocabulary through clustering technique. At VIII class of SMP
Al-Kautsar BKUI Jakarta. Academic year 200132014. Related to the discussion of the finding, it is divided into three parts. Those are before applying the action,
the implementation of the action and discussion of the data after implementation the action.
A. Before Implementing the Action
There are three parts related to the fact-finding before implementing the action. Those are pre interview, pre observation, and pretest. Those explanations
as following:
1. The Result of Pre Interviewed
Pre-interview conduct in this study was unstructured interview. The writer asked the question divided into three categories of questions, involving the
general condition in English class, especially in vocabulary learning, the strategy in teaching vocabulary used by the teacher, and the difficulties faced by the
students in vocabulary learning and asking about clustering strategy. It was held on January 20
th
2014 stated at 10:00 A.M and finished at 11:00 A.M. First category discussed about the general condition in English class
especially in vocabulary learning. The teacher said that most of the students who did not like English class gained low competence in English. Besides, they still
faced problem in following the English lesson. They thought that English is complicated subject to be learned.
The second category discussed about the strategy used by the teacher in teaching vocabulary, the teacher said that sometimes he said the vocabulary and
give the meaning of it or finding it in a dictionary. The researcher asked the teacher about vocabulary clustering strategy. He hoped that this technique
clustering technique can b e effective in retaining students’ English vocabulary.
