1. 1 Pearson’s Linear Correlation Coefficient  Given: At a concert, the number of tattoos, x, and the number of piercings, y, that a person had was recorded:  Find: The linear correlation coefficient, r x y 25 87 56 34 68

2. 2 The Formula  The value of Pearson’s linear correlation coefficient, r, is found using formula 3.2: r = SS(xy) SS(x) SS(y)  Note:The formula for r uses the 3 SS values found as preliminary calculations If you do not know the values of SS(xy), SS(x) and SS(y), you need to obtain them before continuing (See Animated Tutorial “Bivariate Data - Preliminary Calculations” for assistance in completing these preliminary calculations)  Once you have the values of SS(xy), SS(x) and SS(y), you are prepared to proceed with the calculations of r

3. 3 Calculating r  The preliminary calculations yielded: Notes:1) Do not use rounded values for the SS values 2) Round only when the calculation is completed 3) Typically, r is rounded to the nearest hundredth SS(x) = 22.8SS(y) = 10SS(xy) = 12 = 12 (22.8) (10)  = 12 228  0.7947 r = 0.79 = 12 15.099669 =0.7947r = SS(xy) SS(x) SS(y) 