to find out the correlation coefficient between two variables. The final score of variables X and Y are presented in the following table:
Table 4.5 The Final Score of Critical Thinking and Argumentative Writing
No. Participants
X Y
X2 Y2
XY
1. 1
65 77
4225 5929
5005 2.
2 67.5
75 4556.25
5625 5062.5
3. 3
70 73.5
4900 5402.25
5145 4.
4 77.5
77.5 6006.25
6006.25 6006.25
5. 5
80 81
6400 6561
6480 6.
6 82.5
81.5 6806.25
6642.25 6723.75
7. 7
82.5 70.5
6806.25 4970.25
5816.25 8.
8 70
75 4900
5625 5250
9. 9
85 83.5
7225 6972.25
7097.5 10.
10 65
72.5 4225
5256.25 4712.5
11. 11
72.5 75.5
5256.25 5700.25
5473.75 12.
12 82.5
83 6806.25
6889 6847.5
13. 13
77.5 68
6006.25 4624
5270 14.
14 70
81.5 4900
6642.25 5705
15. 15
85 83
7225 6889
7055 16.
16 62.5
73.5 3906.25
5402.25 4593.75
17. 17
55 67.5
3025 4556.25
3712.5 18.
18 67.5
69.5 4556.25
4830.25 4691.25
19. 19
70 83.5
4900 6972.25
5845 20.
20 75
64.5 5625
4160.25 4837.5
21. 21
57.5 72.5
3306.25 5256.25
4168.75 22.
22 92.5
84.5 8556.25
7140.25 7816.25
23. 23
77.5 74.5
6006.25 5550.25
5773.75 24.
24 92.5
81.5 8556.25
6642.25 7538.75
No. Participants
X Y
X2 Y2
XY
25. 25
60 77
3600 5929
4620 26.
26 72.5
79.5 5256.25
6320.25 5763.75
27. 27
82.5 75
6806.25 5625
6187.5 28.
28 70
76 4900
5776 5320
29. 29
72.5 75.5
5256.25 5700.25
5473.75 30.
30 77.5
77.5 6006.25
6006.25 6006.25
31. 31
42.5 68
1806.25 4624
2890 32.
32 82.5
88.5 6806.25
7832.25 7301.25
33. 33
67.5 63
4556.25 3969
4252.5 34.
34 65
73.5 4225
5402.25 4777.5
35. 35
82.5 80.5
6806.25 6480.25
6641.25
Total N= 35
2557.5 2664
190706.25 203908.75 195861.3
From the table above, it results the following data: N
: 35 ∑ : 2557.5
∑ : 2664 ∑ Y : 195861.3
ΣX² : 190706.25 ΣY² : 203908.75
The data above shows that N indicates the number or sum of the participants:
∑ indicates the sum of variable X score: ∑ indicates the Sum of variable Y score: while,
∑ Y is the symbol of the sum of the variables paired scores.
From those data, the correlation coefficient between two variables is tested using Pearson Product Moment and it is symbolized with
. The calculation of is presented in details as follow:
∑ ∑ ∑ √[ ∑
∑ ] [ ∑
∑ ]
√[ ] [
]
√[ ] [ ]
√
√
After being manually calculated, it is found that the Pearson Product Moment or
score is 0.573. The result above is in similarity with the result of two- tailed Pearson Product Moment calculation using SPSS software. The result
is presented in the following table:
Table 4.6 The Results of Pearson Product Moment Correlation
X Y
X Pearson Correlation
1 .573
Sig. 2-tailed .000
Sum of Squares and Cross-products 3826.071
1235.500 Covariance
112.532 36.338
N 35
35
Y
Pearson Correlation
.573
1
Sig. 2-tailed .000
Sum of Squares and Cross-products 1235.500
1216.400 Covariance
36.338 35.776
N 35
35 . Correlation is significant at the 0.01 level 2-tailed.
Table 4.6 above represents the result of Pearson Product Moment Correlation Coefficient using SPSS software. It reveals that the coefficient
correlation of the two variables critical thinking skill and argumentative writing skill is .573. It means that the score of correlation coefficient
is higher than score in the r table rt. In this case, the correlation coefficient
found is 0.573; while the r table rt score in the significance of 0.05 5 is 0.304 and
0.393 in the significance of 0.01 1 See the Appendix 14 for r table rt. Therefore, the
= 0.573 = 0.304 and
= = 0.393.
Meanwhile, to know the size of the correlation or the contribution of variable X critical thinking skill towards variable Y argumentative writing
skill, the determination coefficient R is calculated. The detail calculation of R is presented below:
R= x 100
R= x 100
R= 0.328 x 100
R= 32.8
Based on the result of determination coefficient calculation above, it is resulted that the determination coefficient score is 32.8. It means that the
contribution of variable X critical thinking towards variable Y argumentative writing is 32.8.
2. Testing Hypotheses
After both of the data critical thinking skill and argumentative writing skill are analyzed; then, the hypotheses of this study are tested. The hypotheses
are tested by comparing the t-table and the t-test. The hypotheses of this study are: :
= 0 or if ,
is accepted, and is rejected.
: 0 or if t
, is accepted, and
is rejected. The descriptions of those hypotheses are presented detail as follow:
1. The null hypothesis
: There is no significant relationship between critical thinking skill and argumentative writing skill of the twelfth grade students of
SMA Kharisma Bangsa, academic year 2015 2016. 2.
Research hypothesis : There is a significant relationship between critical
thinking skill and argumentative writing skill of the twelfth grade students of SMA Kharisma Bangsa, academic year 2015 2016.
According to the research finding, the calculation of score is obtained
0.573. Then, the score is compared with the r table rt with the the
level of significance at 0.05 5 and the level of significance of 0.01
1 with df= 33. In order to test the research hypotheses of this study, the value of t-test is
calculated. The calculation of t-test presented in detail as follow: R Product Moment Correlation Coefficient = 0.573
N Number of Participants = 35 Df Degree of Freedom
= 33 t
√ √
t
√ √
t t
479 4.01
Based on the calculation above, it is found that the score of t= 4.01. The result of t-test is compared with the t-table in the level of significance of 0.05
5 and the level of significance of 0.01 1. The t-table are obtained respectively in 1.67 and 2.43 with interpolation see appendix 15. Therefore,
the t= 4.01 = 1.67 and t= 4.01
= 2.43. Next, to determine the correlation between critical thinking skill and
argumentative writing skill employed to the population is tested with the following criteria:
1. :
= 0 or if ,
is accepted, and is rejected.
2. :
0 or if t ,,
is accepted, and is rejected.
Due to the fact that the t-test value are higher than t-table value, t and t
, therefore, is accepted and
is rejected. This result can be interpreted that there is significant relationship between critical thinking skill and
argumentative writing skill of the twelfth grade students of SMA Kharisma Bangsa, academic year 20152016.
C. Discussions
Based on the data description and statistical calculation above, it can be interpreted that the critical thinking skill of the twelfth grade students of SMA
Kharisma Bangsa is averagely fairly good. The average score mean of critical thinking ability is 73.
1 and the students’ argumentative writing skill in average is fairly good as well. The mean score of students’ argumentative writing skill is
76.0. It is slightly better than the students’ critical thinking skill.
According to the results of the calculation of data analysis, the score of correlation coefficient
is higher than score in the r table rt. In this case, the correlation coefficient
found is 0.573; while the r table rt score in the significant of 0.05 5 is 0.304 and 0.393 in the significant of 0.01 1.
Therefore, the = 0.573
= 0.304 and = 0.573
= 0.393. It means that a correlation exists between two variables. In other words, there is
significant relationship between critical thinking skill and writing skill in term of argumentative writing.
In addition, based on the calculation of the t-test, it is found that the score of t= 4.01 and it is higher than the score of t-table. The result of t-test is compared
with the t-table in the level of significance of 0.05 5 and the level of
significance of 0.01 1. The t table are obtained respectively in 1.67 and
2.43 with interpolation see appendix 15. Therefore, the t= 4.01 =
1.67 and t= 4.01 = 2.43. Due to the fact that the result of t-test is
higher than t-table, consequently, is accepted and
is rejected. This result can be interpreted that there is significant relationship between critical thinking
skill and argumentative writing skill of the twelfth grade students of SMA Kharisma Bangsa, academic year 20152016.
Moreover, based on the calculation of determination coefficient R obtained, critical thinking skill has 32.8 contribution towards argumentative
writing skill of the twelfth grade students of SMA Kharisma Bangsa in academic year 20152016. In other words, the skill of students in argumentative writing is
influenced by 32.8 of their critical thinking skill and 68.2 by other factors, for example,
writers’ background of knowledge, grammatical understanding, vocabulary mastery, and cultural background and so on.
Besides, the can also be interpreted with the table of r score
interpretation the table can be seen in the third chapter or in Table 3.1. Based on Table 3.1, the
score resulted in this study is 0.573. It places in the range of 0.39
—0.69. It indicates that there is moderate or average relationship between two variables critical thinking skill and argumentative writing skill. Hence, it
can be interpreted that the critical thinking skill of twelfth grade students of SMA Kharisma Bangsa has moderate correlation with their argumentative writing skill.
This is in accordance with Farahnaz Rimani opinion that critical thinking skills including analysis, evaluation, and inference have positive relationship with the
quality of writing.
1
Therefore, the students who have good critical thinking skill, they must have good writing skill as well, particularly in argumentative writing.
Meanwhile; the students who lack of the ability to think critically, they usually
1
Farahnaz Rimani Nikou, Alireza Bonyadi and Negin Amirikar, Investigating the Relationship between Critical Thinking Skills and the Quality of Iranian Intermediate TEFL
Students’ Writing, Australian International Academic Centre, Australia, Vol. 6 No. 2; April 2015.
have poor argumentative writing skill. Because having critical thinking will make the students be able to develop the idea critically and creatively.
D. Limitation
There were some limitations that were found in this study. The first limitation was the number of participants which were only 35 students. Although
the number of participants has already met the requirements, it is still better to have great numbers of participants to make the result more valid and credible. In
correlational study, the greater numbers of the participants, the more valid and reliable are the data.
2
Next, the critical thinking test instrument which was conducted from Cornell Critical Thinking Test CCTT also became the limitation in this study.
The language used in CCTT was English in which a foreign language for the participants. This, might cause students had problems in understanding the
questions of the test and influenced the test results. In the other researches which used the same instrument CCTT
—the research that was conducted by Malaysian researchers Rosyanti and Rosna Awang: 2008, Rozaidi Ismail:
2003 — used the participants’ native language, i.e. Bahasa Malaysia. Therefore,
the research finding and results may be more accurate. It is because using participants’ native language leads the participants more understand the test
questions. Another problem came from the raters who were rate and score the
students’ writing. The second rater who was the researcher herself seems to be less qualified to score the students writing because of her inexperienced in
assessing writing. Therefore, it is better to have the rater who has experience and better understanding about assessing writing.
Of course, a large limitation in the study could come from many factors such as students’ condition and situation when conducting the tests both critical
thinking test and argumentative writing test and the environment in which the
2
Gay, op. cit., p. 207.
