b. Sample
Sample is a selected group of subjects for a study where the individuals represent the larger group.
3
The strategy of sampling was Non-probability Sampling; it means that this kind of sampling does not
equally give the opportunity for every population to be selected as the sample.
4
The technique of the sample was total sampling; where all populations become the main sample. The sample of this research was;
the A class with 16 students as the experimental class and B class with 16 students as controlled class.
D. Validity of the Instrument
An instrument which is going to be tested to students should have measured what should be measured it is well-known as validity.
Heaton defined “validity is the extent to which it
measures what it is supposed to measure”
5
. The instrument of this research is based on the content of the English syllabus,
“Mengungkapkan makna dan langkah retorika dalam esei pendek sederhana dengan menggunakan
ragam bahasa tulis secara akurat, lancar dan berterima untuk berinteraksi dengan lingkungan sekitar dalam teks berbentuk descriptive dan recount
”. The students should attain those objectives in learning descriptive writing, therefore, to
construct the test or instrument and the objective can be reached, it should be guided on its content and it is known as content validity.
Content validity is a kind of validity that depends on the analysis of the language which is being tested and the course objective.
6
Before conducting the test, the writer did the consultation to the advisor about the instrument in order to
make it is compatible and appropriate with the syllabus. The instrument of this research has to be appropriate with the objective of learning descriptive text itself,
the indicator of learning descriptive text and instruction given to students so that there is the appropriateness with the content of the syllabus and the writing
3
L. R. Gay, Educational Research: Competencies for Analysis and Application, Third Edition, Columbus, Ohio: Merrill Publishing Company, 1987, p. 101.
4
Loc. cit,.
5
J. B. Heaton, Writing English Language Tests, New York: Longman Inc., 1988, p. 159
6
Ibid, p. 160.
material which is tested to students and the objective of teaching and learning can be achieved.
E. Reliability of the Instrument
The test also must reliable; it means that the test must be consistent in its measurement.
7
To make the test is reliable; the writer used rubric scoring as Hughes suggested namely analytic scoring to score the
students’ pre-test and post- test. The analytic scoring scores every aspect of content and composition of
writing which is, sometimes, cannot be scored by other scoring. The scales of analytic scoring are derived from John Anderson. Actually, this analytic scoring is
based on oral scoring found by Harris but it also can be a scoring of writing skill. There are some advantages of analytic scoring, the scores are compiled to
consider aspect of performance which it might otherwise ignore, besides, the very fact that the scores have to give a number of scorer will tend to make the scoring
more reliable.
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F. Instrument of the Study
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