In: Math
A. Here is a bivariate data set.
x | y |
---|---|
25.7 | 52.5 |
29.4 | 64.7 |
21.8 | 54.9 |
35 | 63.4 |
31.4 | 74.7 |
21.6 | 46.5 |
40.8 | 69.7 |
37.9 | 77.7 |
16.7 | 41.1 |
29.6 | 78.1 |
13.1 | 45.5 |
36.1 | 78.4 |
32.1 | 68.2 |
45.2 | 76.8 |
36.1 | 57.9 |
Find the correlation coefficient and report it accurate to three
decimal places.
r =
What proportion of the variation in y can be explained by
the variation in the values of x? Report answer as a
percentage accurate to one decimal place.
r² = %
B. Based on the data shown below, calculate the correlation coefficient (to three decimal places)
x | y |
---|---|
1 | 4.97 |
2 | 4.04 |
3 | 3.51 |
4 | 3.78 |
5 | 5.15 |
6 | 7.22 |
7 | 6.69 |
8 | 5.76 |
9 | 6.73 |
10 | 6.6 |
11 | 9.77 |
12 | 8.24 |
13 | 6.91 |
Ans:
a)
x | y | xy | x^2 | y^2 | |
1 | 25.7 | 52.5 | 1349.25 | 660.49 | 2756.25 |
2 | 29.4 | 64.7 | 1902.18 | 864.36 | 4186.09 |
3 | 21.8 | 54.9 | 1196.82 | 475.24 | 3014.01 |
4 | 35 | 63.4 | 2219 | 1225 | 4019.56 |
5 | 31.4 | 74.7 | 2345.58 | 985.96 | 5580.09 |
6 | 21.6 | 46.5 | 1004.4 | 466.56 | 2162.25 |
7 | 40.8 | 69.7 | 2843.76 | 1664.64 | 4858.09 |
8 | 37.9 | 77.7 | 2944.83 | 1436.41 | 6037.29 |
9 | 16.7 | 41.1 | 686.37 | 278.89 | 1689.21 |
10 | 29.6 | 78.1 | 2311.76 | 876.16 | 6099.61 |
11 | 13.1 | 45.5 | 596.05 | 171.61 | 2070.25 |
12 | 36.1 | 78.4 | 2830.24 | 1303.21 | 6146.56 |
13 | 32.1 | 68.2 | 2189.22 | 1030.41 | 4651.24 |
14 | 45.2 | 76.8 | 3471.36 | 2043.04 | 5898.24 |
15 | 36.1 | 57.9 | 2090.19 | 1303.21 | 3352.41 |
Total | 452.5 | 950.1 | 29981.01 | 14785.19 | 62521.15 |
Correlation coefficient,r=(15*29981.01-452.5*950.1)/SQRT((15*14785.19-452.5^2)*(15*62521.15-950.1^2))
r=0.810
r^2=0.810^2=0.656 or 65.6%
b)
x | y | xy | x^2 | y^2 | |
1 | 1 | 4.97 | 4.97 | 1 | 24.7009 |
2 | 2 | 4.04 | 8.08 | 4 | 16.3216 |
3 | 3 | 3.51 | 10.53 | 9 | 12.3201 |
4 | 4 | 3.78 | 15.12 | 16 | 14.2884 |
5 | 5 | 5.15 | 25.75 | 25 | 26.5225 |
6 | 6 | 7.22 | 43.32 | 36 | 52.1284 |
7 | 7 | 6.69 | 46.83 | 49 | 44.7561 |
8 | 8 | 5.76 | 46.08 | 64 | 33.1776 |
9 | 9 | 6.73 | 60.57 | 81 | 45.2929 |
10 | 10 | 6.6 | 66 | 100 | 43.56 |
11 | 11 | 9.77 | 107.47 | 121 | 95.4529 |
12 | 12 | 8.24 | 98.88 | 144 | 67.8976 |
13 | 13 | 6.91 | 89.83 | 169 | 47.7481 |
Total | 91 | 79.37 | 623.43 | 819 | 524.1671 |
correlation coefficient,r=(13*623.43-91*79.37)/SQRT((13*819-91^2)*(13*524.1671-79.37^2))
r=0.799