Correcting Two-Variable Data.
Here is the raw data:
Week / Minutes of Advertising (x-values) / Sales (y-values)
1 / 2 / $1,400
2 / 1 / $920
3 / 3 / $1,100
4 / 5 / $2,265
5 / 5 / $2,890
6 / 4 / $2,200
This is the keystrokes used to enter the data into the HP 10bII Calculator:
Correlation can be calculated with the Yellow shift x,r key followed by SWAP key. In this example it is 0.89953 ( if set to 5 decimal places)
And covariance of x and y can be defined as:
cov xy = correlation* sigma(x) * sigma(y).
Here is the keystrokes to get sigma(x) and then sigma (y):
In this example, we have:
Sigma(x) = 1.63299
Sigma(y) = 773.12623
Covariance = 0.89953 x 1.63299 x 773.12623 = 1,135.66447
The correlation is one of the most common and most useful statistics. A correlation is a single number that describes the degree of relationship between two variables.
Covariance is a statistical measure of correlation of the fluctuations of two different quantities.