the result of t-value, then the t-value was consulted to the t-table to be interpreted. The t-value was tested using this formula:
t
√ √
The descriptions of the formula above are as follow: t : the t- value
r : Correlation coefficient value n : Number or sum of the participants
Then, to know how much contribution of the dependent variables to
independent variable, it can be known by this formula: R= .
In which: R= value of determinant coefficient
r = value of correlation coefficient Besides, to know the level of corellation of two variables covered critical
thinking and argumentative writing skill, the can also be interpreted with the
table of r score interpretation as presented in the following table:
Table 3.1 Table of r Score Interpretation
5
NO. the
“r” score Interpretation
1 0.90
–1.00 Very high
2 0.70
–0.89 High
3 0.40
–0.69 Moderate
4 0.20
–0.39 Low
5 0.00
–0.19 Very low
5
Sugiyono, Statistika Untuk Penelitian Bandung: Alfabeta, 2013, p.231.
Table 3.1 above represents the interpretation of correlation coefficient value
. If the value of is between 0.90
—1.00, it means that the both of the variables analyzed have very high correlation; while if the
score gained ranges between 0.00
—0.19, it can be interpreted that the relationship between two variables analyzed is very low.
G. Statistical Hypotheses
The non- directional two- tail test was used in terms of the statistical hypotheses, which is presented as follow:
: r = 0 or if rt,
is accepted, and is rejected.
: r 0 or if
rt, is accepted, and
is rejected. The descriptions of those formulas are as follow:
1. 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 20152016. 2.
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 20152016.
40
CHAPTER IV RESEARCH FINDINGS AND DISCUSSIONS
This chapter discusses the research findings from which the data were collected and analyzed. The discussion is disributed into data description of
critical thinking skill and argumentative writing skill, data analysis and hypotheses test.
A. Data Description
1. Critical Thinking Skill Data
The ability of students’ critical thinking of SMA Kharisma Bangsa is gained from the result of critical thinking test. The result is determined by
calculating the number of correct answer of the critical thinking test. The answer then is analyzed and scored. This figure below is the illustration of the critical
thinking ability data:
Figure 4.1 Histogram of the Students’ Score Frequency of Critical Thinking Test
Figure 4.1 above shows that from 35 participants who did the critical thinking test, the most frequently appeared score mode are the group score in the
interval of 70 —75; there are 8 students. Besides, there are 2 participants who got
the highest score in the interval of 90 —95. Meanwhile, the lowest score of critical
thinking test is in the interval of 40 —45 with only one student.
Moreover, the descriptive statistic of students critical thinking ability data is described more detail in the following table:
Table 4.1 The Descriptive Statistic of Critical Thinking Skill Data
Mean 73.071
Median 72.500
Maximum 92.5
Minimum 42.5
Range 50,0
Interquartil Range 15.0
Standard Deviation 10.6081
Variance Coefficient 112.532
Skewness .526
Standard Error Skewness .398
Kurtosis .799
Standard Error Kurtosis .778
From the table above, it reveals the data of students’ critical thinking skill based on the descriptive statistic. It is indicated by the mean, median, maximum
and minimum score. In this case, the average score mean of the critical thinking data is 73.071 and the middle point median score is 72.5. Meanwhile, the
minimum score of students critical thinking skill is 42.5 and the maximum score is 92.5. Next, the range of critical thinking skill score is 50.0.
In addition, the dispersion or variability dist ribution of students’ critical
thinking is indicated by the standard deviation, variance coefficient, skewness and
kurtosis. Based on Table 4.1, it shows that the standard deviation of critical thinking data is 10.6081. Next, the variance coefficient score is 112.532, while,
the skewness score is –.526. The kurtosis score as shown in the table above is
.799. The table presented above clearly represents the statistical data of
students’ critical thinking skill in SMA Kharisma Bangsa. It describes the mean, median, range and the mode score, as well as the standard deviation and variance
coefficient score.
2. Argumentative Writing Skill Data
The argumentative writing skill of students of SMA Kharisma Bangsa is determined by result of the argumentative writing test which is conducted directly
after critical thinking test. The students ’ writing then is assessed and rated by two
raters. The first rater is the English teacher of SMA Kharisma Bangsa: while, the writer is being the second rater. The table below describes the data of critical
thinking skill of students SMA Kharisma Bangsa after being rated by 2 raters as follow:
Table 4.2 The Descriptive Statistic of Argumentative Writing Skill Data
of Rater 1 and Rater 2 Descriptive Statistics
Rater 1 Rater 2
Mean 76.2
76.0 Median
76.0 76.0
Mode 82.0
73.0 Maximum
89.0 88,0
Minimum 64.0
62.0 Range
25.0 26.0
Standard Deviation 5.9597
6.0973 Variance
35.518 37.176
Descriptive Statistic Rater 1
Rater 2
Skewness .126
282 Standard Error of Skewness
.398 .398
Kurtosis -.454
-.232 Standard Error of Kurtosis
.778 .778
Sum 2667.0
2660.0
Based on Table 4.2 represented above, it shows the central tendency of argumentative writing skill data between two raters. It indicates that the score
appears the most mode score is 82.0; while, the mode score given by the second rater is 73.0. Next, it is found that the middle scores median based on two raters
are same which the point is 76.0. In addition, the average score mean given by the first rater is higher than the score given by second rater which the mean is
76.20 76.0. Similarly, the maximum and the minimum score given by rater 1 are higher than the second rater given. It shows that the maximum score is 89.0 88.0
and the minimum score is 64.0 62.0. Meanwhile, the variability distribution of argumentative writing data
based on rater 1 and rater 2 is shown in various score. The difference is found in the standard deviation that is 5.9597 and 6.0973. The range score of
argumentative writing data based on the rater 1 is 25.0; while, the range score that is given by second rater is 26.0. The variance coefficients based on the two raters
are 35.518 and 37.176. The scores that are rated by both raters show the difference but not really
significant see the appendix 4. Then, the scores from which each rater is given are compared and summed. The histogram below is the final score of
argumentative writing skill:
