D. Technique of Collecting Data
In collecting data, the instrument that the researcher used is reading test about descriptive test. There are two tests, pre-test and post-test. Pre-test is used to measure
the students’ understanding in reading descriptive text before teacher used numbered heads together as teaching technique. Then, post-test is used when the treatment had
been done. It is to find out the influence of numbered heads together technique that the researcher used in teaching reading descriptive text in experiment class. She
wants to know whether the numbered heads together technique effective or not in improving
students’ reading ability in descriptive text. There are 20 items of multiple
choices in reading test. Both experiment and control classes were given the same test.
E. Internal Validity Control
The instrument of this research is a test. Before the researcher used this instrument to the students as the sample of the research, she tested the instrument to
the eight grade students of SMP Muhamadiyah 17 Rempoa. She tested the VIII B class. In this class, there are 30 students but 5 students were sick. So there only 25
students who did the validity test. The instrument used for pretest and posttest. This step is needed to see the validity of this instrument before it will be applied to the
sample of research. The researcher analyzed this instrument to know the validity by using the formula
of item analysis in test. The validity could be seen from the result of calculation in index of difficulty ID and discriminating power DP of each answer of question.
After the researcher analyzed the calculation of this test, there were 10 itemswere poor, 10 items were mediocre and 10 items were excellent. In order to make the
researcher easier to calculate the data, she eliminated 10 items of poor questions and revised10 items of mediocre questions. So, the final pretest and posttest used in this
research was a test consisted of 20 items of multiple choice about descriptive text.
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