35 Finally, after getting mean of student’s score per action, the researcher
analyzed the student’s improvement score from post- test in each cycle. In analyzing that, the researcher used the formula:
55
P = y1-y X 100
y
P = Percentage of student’s improvement
y = Pre-test result
y1 = Post-test 1
P = y2-y X 100
y
P = Percentage of student’s improvement
y = Pre-test result
y2 = Post-test 2
M. The Trustworthiness of Study
In Trustworthiness, the researcher will discuss about data collection in every observation from performing action research cycles are analyzed
descriptively by using percentage to see tendency that happened in learning activity.
In analyzing the test items, the writer uses four ways to know the trustworthiness of the data as follow:
1. Difficulty item
The researcher analyzes the student’s test. Then categorized into high, medium or low. In this study result the researcher compares the difficulty item
55
David E. Meltzer, The Relationship between Mathmatics Preparation and Conceptual Learning Gains in Physics: A Possible Hidden Variable in Diagnostic Pretest Scores, Iowa:
Department of Physics and Astronomy, 2008, p.3.
36 analysis by comparing students who answer correctly with all of students who
follow the test. The formula which is used is:
56
P = R
T
P = Index of difficulty
R = The total number of students who selected the correct answer T = The total number of students including upper and lower group.
The Criterion using as follows:
57
Table 3.1 The Classification of Difficulty Level
ID REMARK
0 - 0.30 High
0.30 - 0.79 Medium
0.80 – 1.00 Low
2. Discriminating Power
In analyzing success grade and in analyzing the examine test items, the researcher used discriminating power to know performance of the test through
distinguishing students who get high achievement and low achievement. Next the researcher categorized in classification bad, ok, good and very good. Here is the
formula of discriminating power:
58
56
Norman E. Gronlund, Construction Achievement Test, New York: Prentice Hall, 1982, p.102
57
John W. Oller, Language Test at School, London: Longman Group Limited, 1979, p. 246.
58
Wilmar Tambunan, Evaluation of Students Achievment, Jakarta: Depdiknas, 1998, p.139
37
D = U - L N
D = The Index of discriminating power
U = The number of pupils in the upper group who answered the item
correctly L =
The number of pupils in the lower group who answered the item correctly
N = Number of pupils in each of the group.
Then, the writer uses the criterion of discriminating power as follow:
59
Table 3.2 The Classification of Discriminating Power
DISCRIMINATING POWER
REMARK
0.6 – 1.0 Very good
0.4 - 0.6 Good
0.1 – 0.3 Ok
-1 – 0.0 Bad
3. Reliability of Test
