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the lecturing technique for the whole material by the teacher. After getting the test result, the writer scores the students’ work.
4 Comparing both difference between pre-test and post-test result of both experimental and control group by applying t-test formula.
5 Making conclusion of the result.
3.8 Method of Collecting Data
3.8.1 Try-Out
The quality of data, whether it is good or bad, is based on the instrument to collect the data. A good instrument must fulfil validity and reliability. So before the test
was done, the writer had tried out the instrument. The try-out was held on January 12, 2011. It was administered to the students in same level as population. 20
students were taken as the subject of the try-out. They were given 45 minutes in doing the try-out test.
After administering the try-out, the data was analyzed to find out the validity and reliability of the test.
3.8.1.1 Validity
Dealing with validity, Heaton 1979: 152 proposes that validity of a test is the extent to which it measures what is to measure. Every test, whether it is a short,
informal classroom test or public examination, should be valid as the constructor makes it.
The result is consulted to critical value for r-product moment. If the obtained coefficient of correlation is higher than the critical value for research-
31
product moment, it means that a paragraph is valid at 5 alpha level of significance.
To calculate the validity of a test, the writer used this formula:
} }{
{
2 2
2 2
∑ −
∑ ∑
− ∑
∑ ∑
− ∑
= y
y n
x x
n y
x xy
n r
xy
In which, r
xy
= the correlation of the two scores on two halves of the test n
= the number of the students x
= the score of each component y
= the sum of all paragraphs’ scores ∑ xy
= the sum of multiple score with the total score ∑
2
x = the sum of the square score in each component of writing scoring ∑
2
y = the sum of all paragraphs’ score square Arikunto 2006: 170
In this writing, there are five aspects that would be analyzed. They are grammar, vocabulary, spelling, content and fluency.
3.8.1.2 Reliability
Heaton 1979:154 states, reliability is necessary characteristic of any good test: for it to be valid at all, a test must be reliable as a measuring instrument. Reliability is a
consistency of its measurement whether it was administered in different occasion. In this study, the reliability of the test was measured by comparing the obtained value
with research-value product moment. That is, if the obtained value is higher than the table r-value, it can be said that the test is reliable.
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To calculate the reliability of the test, the writer used this formula:
In which index reliablity
number of item item variance
total variance Arikunto 2006: 196
3.8.1.3 The Difficulty of an Item
The index difficulty of an item shows how easy or difficult a particular item proves in a test Heaton 1975: 172. It is usually express as the fraction or
percentages of students who answer the item correctly Arikunto 2006: 211 states that difficulty level is a number that shows the
easy and difficulties of an item. A good test is a test which is not too easy and difficult.
The calculation as follow:
Where, P =
difficulty index
B = number of students getting item correct
JS = total number of respondent
Arikunto 2006: 211
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He classifies the difficulty level of an item as follows: Item with P 0.00 – 0.30 is a difficult item
Item with P 0.31 – 0.70 is a medium item Item with P 0.71 – 1.00 is an easy item
3.8.1.4 Discriminating Power
