Non parametric method: Less power but more robust. Does not assume normal

distribution.

Also varies between -1 and 1

The usual way of writing Spearman Rank Coefficient is:

Where:

d: differences between the ranks of the two variables

n: number of samples

X 4 4 7 25 7 17 16 9 21 7

Y 16 8 8 20 16 15 12 20 25 8

Solution: Step 1. Ho: X=Y

Step 5. Computation of r.

X Y Rank X Rank Y D D²

4 16 9.5 4.5 5 25

4 8 9.5 9 -0.5 0.25

7 8 7 9 -2 4

25 20 1 2.5 -1.5 2.25

7 16 7 4.5 2.5 6.25

17 15 3 6 -3 9

16 12 4 7 -3 9

9 20 5 2.5 2.5 6.25

21 25 2 1 1 1

7 8 7 9 -2 4

Step 6. Decision: Accept Ho since r = 0.594 is less than 0.602. Interpretation: The values of X and Y are not

related.

1. Calculate the correlation between the IQ of a person with the number of hours spent in front of TV per week.

IQ Hours of TV per

week

106 7

86 0

100 27

101 50

99 28

103 29

97 20

113 12

112 6

110 17