In: Statistics and Probability
The following data represent the daily supply (y in
thousands of units) and the unit price (x in dollars) for
a product.
Daily Supply (y) |
Unit Price (x) |
5 |
2 |
7 |
4 |
9 |
8 |
12 |
5 |
10 |
7 |
13 |
8 |
16 |
16 |
16 |
6 |
a. |
Compute and interpret the sample covariance for the above data. |
b. |
Compute the standard deviation for the daily supply. |
c. |
Compute the standard deviation for the unit price. |
d. |
Compute and interpret the sample correlation coefficient. |
Answer a)
Cov(x,y) = 11.429
Answer b)
Based on the above table, the following is calculated:
sy = sqrt(SSYY/(n-1)) = sqrt(112/7)
sy = 4
Answer c)
Based on the above table, the following is calculated:
sx = sqrt(SSXX/(n-1)) = sqrt(122/7)
sx = 4.1748
Answer d)
Correlation coefficient = Cov(x,y)/(sx*sy) = 11.429/(4.1748*4)
Correlation coefficient = 0.6844