Dwi Undayasari, 2013 The Use of Role-
Play i O e of Vocatio al Schools i Su eda g to I prove Stude ts’ Speaking Skill
Universitas Pendidikan Indonesia | repository.upi.edu | perpustakaan.upi.edu
Asymp. Sig. is higher than 0.05, it means that the variance of the experimental and control groups is not homogenous.
3.5.1.3. t-test Computation
The t-test is purposed to determine whether the means of two groups of score differ to a statistically significant degree
Kranzler,1999. The independent t-test can be calculated by using SPSS 16.0 for windows and the independent t-test can be calculated
after normality distribution and variance of homogenity test are fulfilled. The hypotheses used is as follow:
H : There were no significance differences between the
experimental and control groups. H
1
: There were significance differences between the experimental and control groups.
The criteria of independent t-test test by using 5 level of significance p= 0,05, two tailed test are:
If t
obt
t
crit
at 0,05 level, H is not rejected
If t
obt
t
crit
at 0,05 level, H is rejected
Dwi Undayasari, 2013 The Use of Role-
Play i O e of Vocatio al Schools i Su eda g to I prove Stude ts’ Speaking Skill
Universitas Pendidikan Indonesia | repository.upi.edu | perpustakaan.upi.edu
The level of significant criterion for t-test stated that if t
obt
is lower than t
crit
, it means that there were no significance differences between the experimental and control groups. While if t
obt
is higher than t
crit
, it means that there were significance differences between the experimental and control groups.
3.5.1.4. The Effect Size
Effect size refers to effect of the influence of independent variable upon the dependent variable Coolidge, 2000. Coefficient
correlation of effect size formula is as follow:
In which: r = coefficient correlation
t = the value of t
obt
df = the value of degree of freedom The t refers to the t
obt
from post-test data in the independent t- test and df = N-2. The scale of effect size:
Table 3.4
Dwi Undayasari, 2013 The Use of Role-
Play i O e of Vocatio al Schools i Su eda g to I prove Stude ts’ Speaking Skill
Universitas Pendidikan Indonesia | repository.upi.edu | perpustakaan.upi.edu
The Scale of Effect Size Effect Size
r value
Small .100
Medium .243
Large .371
3.5.2. The Questionnaire Data Analysis
