Function Correlation-From-Summaries
(
correlation-from-summaries < n > < x > < x2 > < y > < y2 > < xy > )
Computes the correlation of two variables given summary statistics of the
variables. All of these arguments are summed over the variable: `x' is the sum
of the x's, `x2' is the sum of the squares of the x's, and `xy' is the sum of
the cross-products, which is also known as the inner product of the variables x
and y. Of course, `n' is the number of data values in each variable.