The criteria of the testing are as follow: If
, H is accepted and H
a
is rejected If
, H is rejected and H
a
is accepted
4. Mean
Mean or average is sum of all score divided by number of scores.
7
Moreover, Charles and Dianne adds that mean is score on a test is what is commonly known as the average; that is the sum of all the students’ scores
divided by the number of students
8
. a. Determining mean of gained score of experiment group, the formula :
M
x
= b. Determining mean of gained score of control group, the formula :
M
y
=
5. Range
The symbol of range R and range is the difference between lowest score and highest score.
9
The formula is follow:
Range R = R
max
- R
min
6. Variance
Variance is the amount of dispersion from standard deviation. The formula is:
∑ ∑
7
Prof. Drs.Anas Sudijono, Pengantar Statistik Pendidikan, Jakarta: PT. Raja Grafindo, 2012, p. 79
8
Charles, loc.cit., p. 296
9
Anas, op.cit., p. 144
7. Standard Deviation
Standard deviation is the square root of variance. Standard deviation was aimed to measure the degree of dispersion data had from
mean. The formula is:
S=
√
∑ ∑
or S = √S
2
8. Effect Size
The effect size is used to know the strong or weak of the difference two groups or the relationship between two variables.
10
Moreover, the effect size of
Cohen’s d has formula as follow:
11
d
=
Pooled standard deviation = standard deviation of group 1 + standard deviation of group 2
2
Beside that, there was a Statistical Calculators that called The Effect Size Cohen’s d Calculator for a Student t-Test which automatically
know the range of treatment’s effect.
The directions using The Effect Size Cohen’s d Calculator for a Student
t-Test was : - Search on google
The Effect Size Cohen’s d Calculator for a Student t-Test or
www.Daniel soper.com calculator web
10
Daniel Muijis, Doing Quantitative Research in Education,London: Sage Publications, 2004, p. 139
11
Ibid, p. 136
- Input mean score of group 1 and mean score of group 2 post- test
- Input standard deviation of group 1 and standard deviation of group 2 post-test
- Click calculate and the result will be show
The criteria of effect size range are small, medium, or large. The criteria are:
12
Table 3.2 Criteria of Cohen’s d Effect Size
Effect size range Criteria
0.2 Small
0.5 Medium
0.8 Large
G. Statistical Hypothesis of Study
