52
1812.95 – 2176.2
t =
2209 + 4914
1 + 1 20 + 20 – 2
20 20
t = + 7.25 2173
2 38
20
t = +7.25 1.87631578947368
t = +7.25 1.369786768
t = 5.293
4.3 Test of Significance
To examine whether the difference between the means of the control and experimental group id statistically significant, the t-value obtained
should be consulted with the critical value in the t-table. I used the 5 0.05 level of significance.
The number of subjects from both groups was 40, so the degree of freedom was 38, which was obtained from the formula:
Σ
Nx +
Σ
Ny - 2. For five percent alpha level and 38 Degree freedom.
The t-table was 2.42 The obtained t-value was 5.293 so the t-value was higher than the critical value. Since the obtained t-value was higher
53
than the critical value on table 5.293 2.42 the difference was statistically significant. Therefore, based on the computation there was
significant difference between teaching vocabulary after and before adding a game. It could be seen by the result of the test where the students’ score was
higher after the treatment.
4.4 Difference of Average Scores Mean between the
Experimental and the Control Class
The experimental class and the control one were used to play a flash game in computer laboratory as media to teach vocabulary was more
effective than expository one. Considering the result of the test gained by two classes, we can see
which class got better achievement. The average of the control group on Pre-Test
Mc =
Σ
Xc Nc
Mc = 1308
20 Mc =
65.4 The average of the control group on Post-test
Mc =
Σ
Xc Nc
Mc = 1397
20 Mc =
69.85 The rise of the average scores:
54
69.85 - 65.4 = 4.45 For the control group, the average after the treatment increased only
4.45 point. The average of the experimental group on Pre-Test
M
E
=
Σ
X
E
N
E
M
E
= 1376
20 M
E
= 68.8
The average of the experimental group on Post-Test M
E
=
Σ
X
E
N
E
M
E
= 1610
20 M
E
= 80.5
The rise of the average score: 80.5 - 68.8
= 11.7 For the experimental group, the average after the treatment increased
11.7 point. After looking at the different development on the average between the
two classes, there was different achievement. The experimental class got better development, the average increased 11.7 point from 68.8 to 80.5 ,
whereas the control class only increased 4.45 from 65.4 to 69.85.
55
4.5 Discussion of Research Findings
