1. Correlation coefficient
Spearmans Ranks
Correlation coefficient

2. Don’t worry it’s not as bad as it looks!
What is spearmans rank
Spearman’s rank is a formula that is used to determine the correlation between two sets of data
It is measured -1 and 1 (-1 = strong negative 0 = no correlation and +1 is strong positive)
The formula is
Don’t worry it’s not as bad as it looks!

3. Step 1
Collect and display your data on age and shoe size for the 10 people in a table like this

4. Step 2 Rank your data 1=your smallest number
If the same number appears more than once take the average number between them and award each with that but count each one as itself

5. Stage 3
Find the difference (D) between the two ranks

6. Stage 4
square the differences to get rid of the negatives

7. Stage 5
Total the squared differences

8. Stage 6
Put the data into the formula

9. Stage 7
∑d² = 70
6 x 70=420

10. Step 8
n = 10
10(10² - 1)
990

11. Stage 9
420 ÷ 990 = 0.424

12. Stage 10
= 0.567

13. What does this mean? Our result looks good but…… -1 11
Strong negative correlation
Strong positive correlation
No correlation

14. What does this mean? 5% level 1% level 0.567 is not high enough!
- it looked good BUT…

15. Not a SIGNIFICANT result!!

16. Graph for a comparison……