Question

Determine the value of the coefficient of correlation, r, for the following data.

X    4   6   7 11 15 17 21
Y 18 13 13 8   7   7    6

(Round the intermediate values to 3 decimal places. Round your answers to 3 decimal places.)

r = ___

Answer 1

= X /n = 81 / 7 = 11.571

= Y / n = 72 / 7 = 10.286

X² = 1177 , Y² = 860, X Y = 679

Sxx = X² - n ² = 1177 - 7 * 11.571² = 239.784

Syy = Y² - n ² = 860 - 7 * 10.286² = 119.387

Sxy = X Y - n = 679 - 7 * 11.571 * 10.286 = -154.135

r = Sxy . sqrt ( Sxx * Syy)

= -154.135 / sqrt [ 239.784 * 119.387 ]

= -0.911