Correlation
www.casiomedia.co.uk › pdf › Correlation3. The product moment correlation coefficient r is given by xx yy xy s s s r. = Where ∑ ∑ = − n x sxx x 2 2 (); ∑ ∑ = − n y syy y 2 2 and ∑ ∑∑ = − n x y sxy xy Use the calculations screens to calculate s xx, s yy and s xy and hence find r. Compare your value for r with the correlation coefficient we found earlier.