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degree α= 0.05. The two groups are homogeneous if the values of
2
are smaller than
2
t
. The procedure of this test is as follows:
1
2 1
2 1
2 1
n n
X X
s
1
2 2
2 2
2 2
n n
X X
s
1
2 3
2 3
2 3
n n
X X
s
1
2 4
2 4
2 4
n n
X X
s
1
1
2 2
i i
i
n s
n s
log
2
s
B = log
2
s
1
i
n
2 2
log 1
10
i i
o
s n
B In
2. Hypothesis Testing
The test for the hypothesis in this research uses Analysis of Variance ANOVA. It is also used to examine the significant effects of two independent
variables to dependent variable. Furthermore, ANOVA is also used to examine the significant interaction between the two independent variables to the dependent
variable.
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a. The total sum of squares:
2 2
2
N X
X x
t t
t
b. The sum of squares between groups:
N X
n X
n X
n X
n X
x
t b
2 4
2 4
3 2
3 2
2 2
1 2
1 2
c. The sum of squares within groups:
2 2
2
b t
w
x x
x
d. The between-columns sum of squares:
N X
n X
n X
x
t c
c c
c b c
2 2
2 2
1 2
1 2
e. The between-rows sum of squares:
N X
n X
n X
x
t r
r r
r br
2 2
2 2
1 2
1 2
f. The sum of squares interaction:
2 2
2 int
br bc
b
x x
x x
g. The number of degrees of freedom associated with each source of variation:
df for between – columns sum of squares = C – 1
df for between – rows sum of squares = R – 1
df for interaction = C – 1 R – 1
df for between – groups sum of squares = G – 1
df for within – groups sum of squares = ∑n – 1
df for total sum of squares = N – 1
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Where: C = the number of columns
R = the number of rows G = the number of groups
n = the number of subjects in one group N = the number of subjects in all groups
3. Tukey Test
The ANOVA test is used to find out if there is a significant different between groups. However, the analysis only indicates that there is a difference
between group means, but it does not show the means difference between cells. Thus, a post hoc test needs to be done. Tukey test is post hoc test designed to
perform a pair wise comparison of the means to see where the significant difference is. The formula of the Tukey test is as follows:
a. Collaborative Writing Method compared with Direct Instruction Method in
teaching writing. q =
n nce
Er r or Var ia X
X
c c
2 1
b. Students having high creativity are compared with students having low
creativity. q =
n nce
Er r or Var ia X
X
r r
2 1
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c. Collaborative Writing Method compared with Direct Instruction Method in
teaching writing for students having high creativity. q =
n nce
Er r or Var ia X
X
r c
r c
1 2
1 1
d. Collaborative Writing Method compared with Direct Instruction Method in
teaching writing for students having low creativity. q =
n nce
Er r or Var ia X
X
r c
r c
2 2
2 1
or q =
n nce
Er r or Var ia X
X
r c
r c
2 1
2 2
The analysis of the result of the computation or q
o
is compared with q
t
, if q
o
q
t
, the difference is significant. To know which one is better, the means are compared.
4. Statistical Hypotheses
