problems associated with the analysis of problems, namely item difficulty, item discrimination and patterns of the answers.
This measurement of items is conducted in order to evaluate the effectiveness of the items. In this study, however, the writer only calculated item
facility and item discrimination of the test.
3.7.3.1 Item Facility known also as Item difficulty
According to Brown 2004:58 item facility is the extent to which an item is easy or difficult for the proposed group of test-takers. If the item is considered as an
easy item, it is seen when there are a great number of test-takers who answer the item correctly. However, if the item is considered as a difficult one, it is seen
when there are a great number of test-takers who answer the item incorrectly. In order to calculate the item facility, the following formula can be used.
P =
��
where: P = the index of difficulty
B = the number of students who answered the item correctly. Js = the number of the test-takers
Arikunto, 2009:207 According to Arikunto 2009:210 the index of difficulty can be classified
into the following. Interval
Criteria 0.00 P
≤ 0.30 0.31 P
≤ 0.70 Difficult
Medium
0.71 P ≤ 1.00
Easy
3.7.3.2 Item Discrimination known also as item differentiation
Brown 2004:59 states that item discrimination is the extent to which an item differentiate between high-and low-ability test-takers. The following formula can
be used to calculate the item discrimination Arikunto, 2009:213. D =
�
–
�
= PA – PB where,
J : the number of students J
A
: the number of upper group students J
B
: the number of lower group students B
A
: the number of upper group students who answer the item correctly B
B
: the number of lower group students who answer the item correctly P
A
: proportion of upper group students, who answer the items correctly P
B
: proportion of lower group students, who answer the items correctly According to Arikunto 2009:218 the discrimination index can be
classified into the following. Interval
Criteria 0.00 D
≤ 0.20 0.21 D
≤ 0.40 0.41 D
≤ 0.70 0.71 D
≤ 1.00 Poor
Satisfactory Good
Excellent
3.8 Method for Collecting the Data
Some steps were done in chronological ways to conduct this study. 1.
The researcher chose eighth grade students of SMPN 39 Semarang as the population. There were 285 students divided into 9 classes; six classes
consisting of 32 students and three classes consisting of 31 students. 2.
The researcher did try out tests. Try out tests were held in a class which belongs to neither the experimental nor control group.
3. The researcher analysed the result of try out tests. The writer analysed the
validity and reliability of the test. If the test was not valid or reliable, then, a revision, commutation, or deletion should be made.
4. The researcher selected two classes as the samples by using nonprobability
sampling technique. Those two classes were randomly assigned into two groups. One group was as the experimental group and another was as the
control group. 5.
The researcher gave a pre-test for both groups. Then, the writer scored the result of the pre-test.
6. The researcher gave treatment to the experimental group subtitled English
songs, while the control group used Grammar Translation Method. The treatment was given in three meetings.
7. The researcher gave a post-test for both groups. Then, the writer scored the
result of the post-test.
