The scores is explained as follow: a.
If the students choose A, the score is 3 b.
If the students choose B, the score is 2 c.
If the students choose C, the score is 1
3.5 Procedures of collecting Data
This subchapter discusses try out, validity, reliability, item difficulty, discriminating power, pretest and posttest. Each of this discussion is presented as
follows:
3.5.1 Try Out
Before the students got the pretest, I had to give try out first to the other class. Try out test was necessary since the result will be used to make sure that
measuring instrument has such characteristic as validity and reliability. After scoring the result of try out, I had to analyze the data to find out its
validity and reliability. The characteristics of a good test are reliability and validity of the test.
To know the quality of the test in pre test and posttest, I analyzed the validity and reliability. Besides validity and reliability of the test, I also analyzed
the items of the test to find out the difficulty index and discriminating power. The more detail discussion was given below.
3.5.2 Validity
The validity is one criterion of an effective test and it is the most important principle when we make a test. The validity is the extent to which
inferences made from test result are appropriate with the purposes of the test. Tuckman 1978:163 says that “the validity of the test represents the extent to
which a test measures what it purports to measure”. From that definition, I can say in simple words, validity is an important criterion to know the quality of the test.
Based on Brown 2004:22 “a valid test reading ability actually measures reading ability-not 2020 vision, nor previous knowledge in subject, nor some
other variable of questionable relevance”. To conduct the test validity, I used the formula which is called “product moment” formula as the following:
2 2
2 2
Y Y
N X
X N
Y X
XY N
rxy
Where: rxy
: Coefficient of correlation between x and y variable or validity of each item
N : the number of the students or subjects participating in the test
X : the sum of scores in each item
Y : the sum of total scores from each student
2
X : the sum of the square scores in each item
2
Y : the sum of the square scores from each student
XY : the sum of multiple of scores from each student with the total score in each item
Arikunto, 2006:170
This formula was used for validating each score, and the result was consulted to critical value for r-product moment. When the obtain coefficient of
correlation was higher than the critical value for r-product moment, it meant that a scoring is valid at 5 alpha level of significances. The result was being consulted
with r product moment, r x y r was valid.
3.5.3 Reliability
