In: Statistics and Probability
Here is a bivariate data set.
| x | y |
|---|---|
| 27.2 | 91.8 |
| 19 | 117 |
| 19.5 | 82.6 |
| 25.9 | 192.3 |
| 47.7 | 95.2 |
| 15.7 | 18.6 |
| 4.6 | 34.7 |
| 24.1 | 34.3 |
| 24.7 | -39 |
| 22.4 | 29.2 |
| 52.7 | 39.1 |
| 7.6 | 81.3 |
| 28.2 | 131.4 |
| 16.8 | -42.6 |
| 25.4 | 70.6 |
| 24.9 | 65.9 |
| 11.1 | 5.7 |
| 5.7 | -74.3 |
| 28.7 | -20.3 |
| -3.8 | 54.4 |
Find the correlation coefficient and report it accurate to three
decimal places.
r =
Solution :
| X | Y | XY | X^2 | Y^2 |
| 27.2 | 91.8 | 2496.96 | 739.84 | 8427.24 |
| 19 | 117 | 2223 | 361 | 13689 |
| 19.5 | 82.6 | 1610.7 | 380.25 | 6822.76 |
| 25.9 | 192.3 | 4980.57 | 670.81 | 36979.29 |
| 47.7 | 95.2 | 4541.04 | 2275.29 | 9063.04 |
| 15.7 | 18.6 | 292.02 | 246.49 | 345.96 |
| 4.6 | 34.7 | 159.62 | 21.16 | 1204.09 |
| 24.1 | 34.3 | 826.63 | 580.81 | 1176.49 |
| 24.7 | -39 | -963.3 | 610.09 | 1521 |
| 22.4 | 29.2 | 654.08 | 501.76 | 852.64 |
| 52.7 | 39.1 | 2060.57 | 2777.29 | 1528.81 |
| 7.6 | 81.3 | 617.88 | 57.76 | 6609.69 |
| 28.2 | 131.4 | 3705.48 | 795.24 | 17265.96 |
| 16.8 | -42.6 | -715.68 | 282.24 | 1814.76 |
| 25.4 | 70.6 | 1793.24 | 645.16 | 4984.36 |
| 24.9 | 65.9 | 1640.91 | 620.01 | 4342.81 |
| 11.1 | 5.7 | 63.27 | 123.21 | 32.49 |
| 5.7 | -74.3 | -423.51 | 32.49 | 5520.49 |
| 28.7 | -20.3 | -582.61 | 823.69 | 412.09 |
| -3.8 | 54.4 | -206.72 | 14.44 | 2959.36 |
| n | 20 |
| sum(XY) | 24774.15 |
| sum(X) | 428.10 |
| sum(Y) | 967.90 |
| sum(X^2) | 12559.03 |
| sum(Y^2) | 125552.33 |
| Numerator | 81125.01 |
| Denominator | 326965.72 |
| r | 0.2481 |
The correlation coefficient r ,

r = 0..2481
Answer : The correlation coefficient r is 0.248