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4.2.1 Normality
Before the t-test computation, the researcher had to make sure that the data were
normal. table of Normality
No Control Group X
2
Experimental Group X
1
Pretest Posttest Pretest Posttest 1 50 60 50 60
2 55 62 55 63 3 55 63 55 66
4 56 63 57 68 5 58 64 58 68
6 58 64 60 74 7 60 66 61 74
8 60 69 61 74 9 62 69 62 74
10 62 70 65 74
11 65 70 65 75
12 65 70 69 76
13 65 71 69 76
14 66 71 69 76
15 66 71 69 76
16 66 71 69 76
17 66 72 70 76
18 66 72 71 79
19 66 72 71 80
20 68 74 72 81
21 68 74 73 81
22 71 75 73 82
23 71 75 74 82
24 72 75 74 82
25 72 76 75 83
26 73 77 75 84
27 75 77 75 84
28 75 78 77 85
29 76 78 77 87
30 77 83 80 90
Total 1967 2132 2027 2306
Mean 66 71 67 77
Variance 32.6 22.28 47.47 31.47
SD 5.71 4.72
6.89 5.61
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After getting the data of experimental and control group, I analyzed the normality. I found that the X
2
of pretest and posttest of experimental group was 3.73 and 3.21 and the X
2
of pretest and posttest of control group was 2.36 and 3.31.
Then, the results were consulted with critical value of X
2
αdk with α = 0.05 and dk = 1, whose result is 3.84. Since the value of X
2
αdk of experimental and control group were lower than 3.84, the data were considered to
be normally distributed.
4.2.2 Homogeneity
Homogeneity is important to check whether the data of each group are homogeneous or not. The computation of homogeneity goes as follow:
In the formula above, F stands for the homogeneity, Ve stands for the variance of experimental group, and Vc stands for the variance of control group.
Use the formula stated above, the homogeneity of pretest of experimental and control group is computed as follow:
F = 1.46 The result was consulted with the value of F table with dk numerator v
1
= 30-1 = 29, dk numerator v
2
= 30-1 = 29, and α = 0.05, squared to v
1
= 30 and v
2
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= 30 is 1.79. Because the F 1.46 1.79, then the data were considered to be homogeny.
While the homogeneity of posttest of both groups is computed as follow:
F = 1.41 The result was consulted with the value of F table with dk numerator v
1
= 30-1 = 29, dk numerator v
2
= 30-1 = 29, and α = 0.05, squared to v
1
= 30 and v
2
= 30 is 1.79. Because the F 1.46 1.79, then the data were considered to be homogeny.
4.3 Computation between the Two Means
Kategori