Low or high correlation?

#1
What does it mean when Pearson correlation gives a value of 0.7-0.8, while spearman correlation gives a value from 0.3-0.4? Pearson reports high correlation while Spearman report weak. Should I conclude that the correlation is weak using spearman since the data seems skewed?
 

noetsi

Fortran must die
#6
There are various opinions about when you should and should not use these two. The one I was taught was that spearman was used for ordinal data and pearson for interval (pearson can not address non-linarity, spearman will work with non-linear data if it is monotonic in nature that is you have one rather than multiple directions for the curve).

I have not heard that logs work to eliminate outliers - they stabilize variance. There are robust methods to address outliers, but they are not simple (such as M estimators).
 

gianmarco

TS Contributor
#7
@John.Thomas:
Regardless the outlier(s), I would like to inspect the whole scatter of data points to have a broader idea of the correlation....
 

noetsi

Fortran must die
#8
One thing a scatterplot may catch is if there is non-linearity and if there is, is it monotonic or not. That will have a lot to do with what approach (pearson or spearman) you use.