Table 3.1 The Activities of the Study
No Activity
Week 1
2 3
4 5
6 7
8
1 Preparation
2 Try-out test
3 Pre-test
4 Treatment
5 Post-test
6 Data processing
7 Report
3.5.1. Try-Out
A good or bad quality of the data is obtained based on the instrument used to collect the data. Good instrument must fulfill important qualification, those are
valid and reliable. To know whether the test is valid and reliable, it had been tried out first to the students in other class beside experimental and control class.
There are 31 students as the respondents of the try-out test. They have to answer the multiple choice test consisting of 20 items and cloze test consisting of
5 items. The students have to complete the test in 45 minutes and will get score
100, if all questions are answered correctly.
3.5.1.1. Validity
Brown 1988: 101 said that “test validity is defined as the degree to which a test measures what it claims to be measuring”. Every test has to be valid, it aims to
provide a true measure of a particular skill which is intended to measure. To calculate the validity of each item, the writer used the Product Moment
Formula:
=
√
in which, r
xy
: validity of the item; N
: total number of students or subject participating; Σх
: item score; Σх
2
: the sum of the square of the item score; Σу
: total score of the item; Σу
2
: the sum of the square of the toatal score; Σху
: the sum of the item score multiplying the score Arikunto, 2002.
The validity computation is consulted to the r
table
of Product Moment by determining the significance level 5 and n which is according to the data. The
instrument is valid if the r
xy
r
table
for α = 5 and N = 31.
3.5.1.2. Reliability
Brown 1988: 98 states that “the reliability a test is defined as the extent to which the results can be considered consistent or stable”. If you give the same
test to the same student or matched students on two different occasions, the test should yield similar results Brown, 2004:20.
To measure the reliability of the test, the writer used the following Kuder-Richardson formula number 20 symbolized KR20:
=
in which, r
11 :
the reliability of the test; : the number of item tes;
p : the proportion of students passing a given item;
q : the proportion of students that did not pass a given item;
∑pq : the sum of p time q;
: the total variants. Carmines and Zeller, 1979: 48
In order to know the level of reliability, the result must be consulted to the table of „r‟ product moment with the number of participant is 31 students and
significance level is 5. If the result of r
11
is higher than the „r‟ product moment, it can be said that the instrument is considered as reliable.
3.5.1.3. Difficulty Level
The index of item difficulty shows how easy or difficult the item is. If the index of item difficulty is high, it is considered the item is easy. If it is low, it will be
considered to be difficult. To calculate the difficulty level of an item, the writer applies the
following formula:
in which, P
: the difficulty level; B
: the number of the students who answered the item correctly;
JS : the number of the students in class Arikunto, 2002: 208.
The criteria used here are: Table 3.2
The index of difficulty
Interval Criteria
0 P ≤ 0.3
Difficult
0.3 P ≤ 0.7
Medium 0.7 P
≤ 1 Easy
Arikunto, 2002: 210
3.5.1.4. Discriminating Power
The discriminating power is used to analyze whether or not a test item has the ability to differentiate students with good mastery from students who have
difficulty in understanding the material. It will measure how well the test items arranged to identify the differences in the students‟ competence.
The following formula is used to calculate discriminating power of the test items:
in which, D
: discriminating power; BA
: the number of the students in the upper group who answered the item correctly;
BB : the number of the students in the lower group who
answered the item correctly; JA
: number of all students in the upper group; JB
: number of all students in the lower group Arikunto, 2002: 213.
The criteria are: Table 3.3
The index of discriminating power
Interval Criteria
0,00 D ≤ 0,2
Poor 0,21 D
≤ 0,40 Satisfactory
0,41 D ≤ 0,70
Good 0,71 D
≤ 1,00 Excellent
Arikunto, 2002: 218
3.5.2. Pre-Test
