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4 Conducting the Posttest
The posttest was conducted after the treatment. It was to identify to what extent the students had understood about the aspects of reading comprehension and how
well they could comprehend a narrative text after the application of TPS technique in teaching-learning of reading comprehension.
The items for the posttest were similar to those of the pretest, only the order of the texts and their corresponding items were rearranged. The items were based on the
following table of specification:
Table 3. Table of Specification of the Posttest
No. Reading Specification
Item Number Percentage
1 Determining main ideas
4, 24, 29 10
2 Inferences
2, 30 6.67
3 References
3, 7, 12, 13, 16, 18, 22, 28
26.67
4 Finding detailed information
1, 5, 6, 9, 11, 14, 15, 17, 19, 20, 23, 27
40
5
Vocabularies 8, 10, 21, 25, 26
16.67
Total 30
100
D. Instrument Used for Collecting the Data
The instrument for data collection —the pretest and the posttest—was previously
qualified through the tryout test. The instrument was tried out to achieve good quality. For such instrument with multiple-choice items, good quality means
having satisfactory degree of validity, reliability, level of difficulty and discrimination power Shohami, 1985.These terms are described on the next
page.
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1 Validity
Validity refers to the extent to which the test measures what it is intended to measure; in other words, it relates directly to the purpose of the test Shohamy,
1985:74. There are four types of validity: face validity, content validity, construct validity, and empirical or criterion-related validity. Face validity concerns only
the surface layout of the test, while criterion-related validity with the measurement of future success, such as in replacement test Hatch and Farhady,
1982:251. In case of the instrument for this research, the other two types of validity
—content and construct validities—are given greater consideration as they are stronger and more relevant.
Hatch and Farhady 1982:251 define content validity as the extent to which the test measures a representative sample of the subject matter content. The focus of
content validity is on the adequacy of the sample and not simply on the appearance of the test. Construct validity, on the other hand, is concerned with
whether the test is actually consistent with the theory of what it means to know the language Shohamy, 1985:74. One of the efforts to achieve validity is to
construct the instrument based on a table of specification that outlines the content and the aspects of reading comprehension skill to measure. The instrument was
constructed based on the initial table of specification presented below:
Table 4. Initial Table of Specificationfor Data Collection Instrument
No. Reading Specification
Item Number Percentage
1 Determining main idea
2, 13, 27, 28, 29, 30, 32 17.5
2 Inference
6, 12, 17, 19, 21, 22, 24, 36 20
3 Reference
3, 9, 14, 15, 25, 34, 38, 40 20
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No. Reading Specification
Item Number Percentage
4 Finding detailed information 1, 4, 7, 8, 10, 11, 18, 23, 37, 39
25 5
Vocabulary 5, 16, 19, 26, 31, 33, 35
17.5
Total 40
100
2 Reliability
Reliability refers to whether the test is consistent in its scoring and gives us an indication of how accurate the test scores are Shohamy, 1985:70. To measure
the reliability of the instrument, split-half method is calculated using Spearman- Brown split-half coefficient:
In which r
sb
is the split-half reliability coefficient and r
xy
represents the correlation between the two halves of the scores on the items i.e. between the sets of scores
on the odd- and even-numbered items. The r
sb
value is categorized as high if falls between 0.90 to 1.00, moderate between 0.50 to 0.89, and lowfrom 0.49 to zero
Hatch and Farhady, 1985:247. The value of r
xy
is, in turn, obtained using Pearson correlation coefficient formula:
where:
