Lecture 2 - Ch 3 - Correlating two sets of data

In the first lecture, we talked briefly about the correlation of two sets of data in a scatter plot. That discussion described the correlation in a qualitative way. Here we define the measure of correlation more precisely with two measures: covariance and coefficient of correlation.

For two sets of data, x and y:

Covariance (x,y) - [ Sum (x_i-x_mean)*(y_i-y_mean) ] / (n-1)

Coefficient of Correlation, r = covar(x,y) / s_x*s_y
where s_x and s_y are the standard deviations of x and y

BTW, I see now that I'm going to need to make some graphics to display these formulas. I'm going to try to learn to use LaTeX for mathematical typesetting. I downloaded LEd, a LaTeX editor, today and I hope to start using it over the weekend. If anyone has experience with LaTeX and any editor, please let me know.