Question

The following data represent the observed relationship between class size and amount of discussion during class meetings in college courses. Calculate the correlation coefficient (Pearson’s r)

Class size	Amount of Discussion
30	55
80	21
24	50
50	32
60	26

Answer 1

Let X denote the class size and let Y denote the amount of discussion.

The following table gives the data.

Class Size (x)	Amount of Discussion (y)	x2	y2	x*y
30	55	900	3025	1650
80	21	6400	441	1680
24	50	576	2500	1200
50	32	2500	1024	1600
60	26	3600	676	1560
x = 244	y = 184	x2 = 13976	y2 = 7666	xy = 7690

The Pearson's correlation coefficient is given by

Therefore, the correlation coefficient is -0.95