Question

An outbreak of the deadly Ebola virus in 2002 and 2003 killed 91 of the 95 gorillas in 7 home ranges in the Congo. To study the spread of the virus, measure distance by the number of home ranges separating a group of gorillas from the first group infected. Here are data on distance and number of days until deaths began in each later group:

Distance X= 1,5,7,6,7,5

Days Y= 3,22,35,35,47,47

find correlation r between x and y

Answer 1

	x	y	x^2	y^2	xy
	1	3	1	9	3
	5	22	25	484	110
	7	35	49	1225	245
	6	35	36	1225	210
	7	47	49	2209	329
	5	47	25	2209	235
Total	31	189	185	7361	1132

Correlation coefficient

"Σν n Σty-Σ ΣΥ Τ. VηΣΙΣ Σ -Σ 2

  

(6 1132) - (31 189) VI6185) (31)2] [(6 7361) (189)2]

=0.8317

We can directly calculate correlation coefficient by using Excel.

Step 1)  Enter data in Excel.

Step 2 )  Then use =CORREL command and select two separate column data  >> ok