37
WhereDPmeans discrimination power, Correct Uthe proportion of upper group students who respond correctly, Correct Lthe proportion of lower group students
who respond correctly, and N the number of test participants. The following criteria are applied to discrimination power Heaton, 1991: 80:
1 If the value is positive, a larger number or more knowledgeable students than less-knowledgeable ones get the item correct. If the value is zero, there is no
discrimination. 2 If the value is negative, more less-knowledgeable students than
knowledgeable ones get the item correct. 3 In general, higher discrimination index is better. In classroom situation, most
items should have discrimination indexes higher than 0.20.
Students‘ responses in the tryout, the pretest, and the posttest were scored using the following formula:
In which S is the score, R the total correct responses, and N the number of items.
E. Hypothesis Testing
The hypothesis is tested using paired-samples t-test as the samples i.e. the means come from the same subjects. The manual formula of paired-samples t-test is
presented below:
38
Where and
represent the means of the samples pretest and posttest, dthe difference scores,
Σd the sum of the difference scores, Σd
2
the square of the sum of the difference scores, d
2
thesquared difference scores, Σd
2
the sum of the squared difference scores, and n the number of participants in each sample. The
hypothesis is one-tailed as it predicts a significant increase after the treatment, with the significance level set at p = 0.05. If the calculated t value is higher than
the t-table value on specific degree of freedom df, the null hypothesis is rejected, and vice versa.
F. Data Analysis
Data analysis was following the steps below: 1 Scoring the pretest and the posttest.
2 Tabulating the results of the pretest and the posttest and calculating the means of both.
3 Testing the hypothesis using paired-samples t-test via SPSS
®
for Windows
®
to see whether the improvement gained by the students after the application of
TPS technique was significant or not. 4 Interpreting the results of statistical calculations and drawing the conclusion.
IV. RESULTS AND DISCUSSIONS
A. Results of the Research
The research was conducted within the schedule summarized below: 1 Observation was conductedon Wednesday morning, July 27
th
, 2011. 2 Tryout test of the instrument was administeredon Thursday morning, July
28
th
, 2011. 3 Pretest was administered on Monday morning, August 1
st
, 2011. 4 The first meeting of the treatment was carried out on Wednesday morning,
August 3
rd
, 2011the teacherexplained about how to determine the main idea of a paragraph or of the whole story, using The Hermit as the reading material
for narrative text. 5 The second meeting of the treatment was carried out on Thursday morning,
August 4
th
, 2011 the teacherexplained about how to find references and inferences, using The Wolf, the Kid, and the Goatas the reading material for
narrative text. 6 The third meeting of the treatment was carried outon Monday morning,
August 8
th
, 2011the teacherexplained about how to find detailed information and how to identify the meaning of a word vocabulary from context, using
The Tiger who would be a Kingas the reading material for narrative text. 7 Posttest was administeredon Wednesday morning, August 10
th
, 2011.
40 The results of the tryout test, the pretest, and the posttest are described in the
following sections.
1. Result of the Tryout Test
The tryout test was administered to the tryout classClass VIIIB to determine the quality of the instrument for this research. Forty multiple-choice items with four
narrative texts were prepared for the tryout test. The test of reliability using split- half method indicates a reliability level of 0.82 see Appendix 5, a relatively high
value. It implies that the instrument would produce consistent results when administered under relatively similar conditions to the same participants at
different times. In other words, the research instrument is reliable. In addition to reliability level, the items of the instrument were subjected to item
analysis, and the result is shown in the tables below, which summarize the difficulty level and the discrimination power.
Table 5. Difficulty Level of the Tryout Items
No. Item Number
Value Range
Criteria 1
17, 19, 31. 0.30
Difficult 2
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 18, 20, 21, 23, 24, 25, 27, 29, 30, 32, 33, 36, 37,
38, 39, 40. 0.30
– 0.70 Average 3
12, 16, 22, 26, 28, 34, 35. 0.70
Easy
