2. PEARSON PRODUCT MOMENT CORRELATION MEASURE OF CORRELATION
2
Testing Correlation
The Pearson Product Moment Correlation formula shows the relationship between X and Y variables. It
can be seen from the coefficient presented by r.
The following values are:
∑X = 1240
∑Y = 2040
∑XY = 101400
∑X2
= 64800
∑Y2
= 168000
The computation as follows:
rxy =
𝑁(∑𝑋𝑌)−(∑𝑋)(∑𝑌)
√[𝑁∑𝑋2−(∑𝑋)2][𝑁∑𝑌2−(∑𝑌)2
=
25(101400)−(1240)(2040)
√[25(64800)−(1240)2][25(168000)−(2040)2
=
2535000−2529600
√[1620000−1537600][4200000−4161600]
=
5400
√[82400][38400]
=
5400
√31641600
=
5400
5625.086
= 0.959
3. PEARSON PRODUCT MOMENT CORRELATION MEASURE OF CORRELATION
3
The result of the computation of the correlation denotes a moderate criterion in reference to the
criteria put forward by Arikunto (1998:260).
Besarnya nilai r Interpretasi
0.800 to 1.000 Tinggi
0.600 to 0.800 Cukup
0.400 to 0.600 Agak rendah
0.200 to 0.400 Rendah
0.000 to 0.200 Sangat rendah (tak berkorelasi).
Based on the criteria above, the result is clear: Since the coefficient of correlation rxy = 0.959, the
relationship between students’ speaking ability and vocabulary mastery is high enough.
Deciding The Acceptance of Hypothesis
The null hypothesis tested sounds there is no significant relationship between students’ speaking ability
and vocabulary mastery. To decide whether or not to reject the null hypothesis and to accept the
alternative hypothesis, the following criterion is applied:
Ho is accepted if rxy ≤ r in the table.
Ho is rejected if rxy ≥ r in the table.
Therefore, after computing rxy, the result has to be distributed to the table of r for the Pearson Product
Moment Correlation Coefficient.
The result of rxy = 0.959
The table value of r = 0.413 in df 23, ∝ = 0.05
It means that rxy ≥ r. Thus, the null hypothesis that there is no significance relationship between
students’ speaking ability and vocabulary mastery is rejected. In other words, the alternative hypothesis
that there is a significant relationship between students’ speaking ability and vocabulary mastery is
accepted. Besides, the data of numbers support the that there is relationship between them.