difference between the two means is Mx-My. It indicated that the use of audio visual aid were effective in improving students’ speaking skill especially in daily
conversation. Hence, I still cannot claim that the method I used is effective in developing students’ speaking skill until I count the significance using t-test.
4.3 The Differences of Two Means
The result of both experimental and control groups could be seen at the table as follow:
Table 4.4 Differences between pretest and posttest score of experimental group
No Respondents
Pretest x
1
Posttest x
2
Differences X
X
2
1 E-1
96 100
4 16
2 E-2
60 92
32 1024
3 E-3
76 92
16 256
4 E-4
96 100
4 16
5 E-5
88 96
8 64
6 E-6
80 92
12 144
7 E-7
72 80
8 64
8 E-8
68 92
24 576
9 E-9
88 100
12 144
10 E-10
88 96
8 64
11 E-11
80 88
8 64
12 E-12
68 92
24 576
13 E-13
72 88
16 256
14 E-14
56 96
40 1600
15 E-15
72 88
16 256
16 E-16
72 96
24 576
17 E-17
64 96
32 1024
18 E-18
72 92
20 400
19 E-19
88 96
8 64
20 E-20
68 84
16 256
21 E-21
72 84
12 144
22 E-22
92 100
8 64
23 E-23
80 100
20 400
24 E-24
72 88
16 256
25 E-25
72 96
24 576
26 E-26
76 84
8 64
27 E-27
76 92
16 256
28 E-28
84 96
12 144
29 E-29
72 92
20 400
30 E-30
88 92
4 16
31 E-31
96 100
4 16
∑ 2404
2880 476
9776 After calculating the experimental group’s score, I computed the mean
score using the formula stated by Arikunto 2006: 312. The mean of experimental group is:
M = 476.0
31 = 15.35
Next, I calculated the sum of experimental group’s score. The sum of experimental group’s score is:
ΣX = Σx − Σx
Nx
ΣX = 9776 − 476
31 ΣX = 9776 − 7308.90
ΣX = 2467.10
Table 4.5 Differences between pretest and posttest score of the control group:
No Respondents
Pretest y
1
Posttest y
2
Differences Y
Y
2
1 C-1
76 80
4 16
2 C-2
72 84
12 144
3 C-3
64 80
16 256
4 C-4
64 80
16 256
5 C-5
80 88
8 64
6 C-6
68 84
16 256
7 C-7
72 80
8 64
8 C-8
68 80
12 144
9 C-9
80 88
8 64
10 C-10
60 76
16 256
11 C-11
68 84
16 256
12 C-12
76 84
8 64
13 C-13
76 88
12 144
14 C-14
76 80
4 16
15 C-15
68 88
20 400
16 C-16
72 84
12 144
17 C-17
64 80
16 256
18 C-18
68 80
12 144
19 C-19
80 80
20 C-20
80 88
8 64
21 C-21
72 84
12 144
22 C-22
72 88
16 256
23 C-23
64 76
12 144
24 C-24
72 88
16 256
25 C-25
84 84
26 C-26
64 80
16 256
27 C-27
64 76
12 144
28 C-28
76 84
8 64
29 C-29
76 84
8 64
30 C-30
68 84
16 256
31 C-31
68 84
16 256
32 C-32
72 84
12 144
33 C-33
76 84
8 64
34 C-34
60 76
16 256
35 C-35
76 84
8 64
36 C-36
72 88
16 256
∑ 2568
2984 416
5632 After calculating the control group’s score, I computed the mean score
using the formula stated by Arikunto 2006: 312. The mean of control group is:
M = 416.0
36 = 11.56
Next, I calculated the sum of control group’s score. The sum of control group’s score is:
ΣY = Σy − Σy
Ny
ΣY = 5632 − 416.0
36 ΣY = 5632 − 4807.11
ΣY = 824.89 To make the analysis more reliable, I analyzed by using t-test formula as
stated in chapter III.
4.4 Test of Significance
