In: Statistics and Probability
The following is a set of data from a sample of n = 11 items: X 8 6 9 4 7 11 13 5 10 16 19 Y 22 15 25 10 19 31 37 13 27 45 54 a. Calculate the covariance. b. Calculate the coefficient of correlation. c. Describe the relation between the two variables X and Y.
X: 8 6 9 4 7 11 13 5 10 16 19
Y: 22 15 25 10 19 31 37 13 27 45 54
n = 11
= 9.8182
= 27.0909
a)
x | y | (x-xbar) | (y-ybar) | (x-xbar)*(y-ybar) |
8 | 22 | -1.8182 | -5.0909 | 9.2562 |
6 | 15 | -3.8182 | -12.0909 | 46.1653 |
9 | 25 | -0.8182 | -2.0909 | 1.7107 |
4 | 10 | -5.8182 | -17.0909 | 99.4380 |
7 | 19 | -2.8182 | -8.0909 | 22.8017 |
11 | 31 | 1.1818 | 3.9091 | 4.6198 |
13 | 37 | 3.1818 | 9.9091 | 31.5289 |
5 | 13 | -4.8182 | -14.0909 | 67.8926 |
10 | 27 | 0.1818 | -0.0909 | -0.0165 |
16 | 45 | 6.1818 | 17.9091 | 110.7107 |
19 | 54 | 9.1818 | 26.9091 | 247.0744 |
Total | 641.1818 |
b)
Standard deviation of x = = 4.6652
Standard deviation of y = = 13.7510
The formula of the coefficient of correlation (r) is
c) r = 0.9995
There is a positive relation between x and y.