> A =

>            1        1000
>            2        1010
>            3        1020
>            4        1030
>            5        1040
>            6        1050
>            7        1060
>            8        1070
>            9        1080
>           10       1090

> If the first column is the variable X and the second column is the variable
> Y I would like to see how correlated the data is. Computing the covariance
> matrix gives:

> C =

>     9.1667   91.6667
>    91.6667  916.6667

> I have read that if an element in C is 0 there is no covariance between the
> corresponding variables, if its positive there is a covariance between the
> two variables and if its negative there is a covariance between X and -Y.

> In C the covariance between X and Y is 91.6667. But how should that number
> be interpretated and does the magnitude have anything to say?

> If I plot the above data X and Y does not seem very correlated (close to
> each other).