spearman's rank

1.= rank you must rank both columns of data in the same way eg smallest to biggest 

2. difference in rank you take them away from each other again must be the same way though out eg right to left cant switch 

3. sum of the difference squared. 

what does n stand for

number of samples

what does d stand for

difference in rank

what does it mean if you calculate a value close to +1 between that and 0.7

strong positive correlation 

what does it mean if you calculate a value is between 0.7 and 0.3 

moderate positive

what does it mean if it 0.3 to 0 

weak at 0 no correlation 

what does 0 to -0.3 

weak negative 

same for all minus number just negative correlation instead 

when do you use spearmen’s rank

when you have pairs of data and are look at the relationship/ correlation of 2 Co variables if there is a significant relationship not caused by chance then this will give you a strong correlation