3.3. Variables
In this sub chapter, the researcher will explain the variables in this research. Firstly, there is a definition of variable and lastly there are two kinds of variables
in this research.
Variable is a character of a group of people, their behavior, or the variant environment of one individual to others Setiyadi, 2006:201. Besides, in order to
assess the influence of the treatment in research. There are two kinds of variables. They are dependent variable and independent variable. Dependent variable is a
variable that the researcher observes and measures to determine the effect of the independent variable. Independent variable is the major variable that a researcher
hopes to investigate. This research consists of the following variables: 1 Students’ reading comprehension is as dependent variable Y, because this
variable is observed and measured to determine the effect of independent variable.
2 K-W-L strategy is as independent variable X because this variable can influence or have effects to the dependent variable.
In conclusion, there are two variables in this research. They are students’ reading comprehension is as dependent variable Y and K-W-L strategy is as independent
variable X.
3.4. Instruments
The data in this research was gained by two instruments:
1. Reading Test
Tthe first instrument in this research was reading test. The researcher checked the students’ reading comprehension achievement by giving two reading tests to the
students. The reading tests were pretest and posttest. The researcher used multiple choice tests because of some reasons, such as it was easy to score. Besides, it
tested the students’ focus. In addition, it was because multiple choices had four options in it which three of them might distract students’ focus of the right
answer. In the reading test, tryout test was used to find out the quality of the research instrument that was used in pretest and posttest. In order to get a good
test, the test item should fulfill some criteria such as validity, reliability, level of difficulty, and discrimination power that would be discussed below.
•
Validity
A test is considered valid if the test measures the object to be measured and suitable with the criteria. The validity of the test is the extent to which it measures
what it supposed to measure is. A test must aim to provide true measure of particular skill that it is intended to measure.
There are five types of validity Setyadi, 2006:22. They are face validity concerns with the layout of the test. They are content validity that represents the
materials to be included, predictive validity that concerns with measuring the success in the future, as in replacement test, construct validity that concerns in
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