# Thread: Basic question on Spearman's correlation coefficient

1. ## Basic question on Spearman's correlation coefficient

Hey guys,

If I understand correctly, when calculating Spearman's correlation coefficient you just rank your variables, and then calculate Pearson's correlation coefficient for those new, ranked variables.

However, while it is possible to calculate confidence intervals for Pearson, this is not possible for Spearman. Another procedure, canonical correlation analysis, also seems to be only possible to Pearson.

My question is: why are these not possible for Spearman? What would go wrong when one just calculated the confidence intervals for Pearson, but using ranked data? Or do a canonical correlation analysis on ranked data?

2. ## Re: Basic question on Spearman's correlation coefficient

I don't work with spearman's rho (there are a lot of spearman's and I assume you mean the ordinal measure of correlation) but it appears that it is possible to generate a CI for it using the Fischer transformation. See "Determing the Significance" below

http://en.wikipedia.org/wiki/Spearma...on_coefficient

This says the same thing

http://www.statsdirect.com/help/defa...s/spearman.htm

3. ## The Following User Says Thank You to noetsi For This Useful Post:

Hombre (02-24-2014)

4. ## Re: Basic question on Spearman's correlation coefficient

Ahhhh that's kind of embarrassing to get a wikipedia link (should've checked that better before asking :-)), but still very helpful, thanks!

5. ## Re: Basic question on Spearman's correlation coefficient

I tend to be nervous about Wiki as it involves stats, because others have raised questions about accuracy at times. It is why I posted a second link.

6. ## Re: Basic question on Spearman's correlation coefficient

Originally Posted by noetsi
I tend to be nervous about Wiki as it involves stats, because others have raised questions about accuracy at times. It is why I posted a second link.
If it makes you feel better I'm actually typically not nervous about Wikipedia. Their math/stats material usually is pretty good! It's always better to look at another resource but I do use wikipedia as a resource more often than you might imagine.

7. ## Re: Basic question on Spearman's correlation coefficient

Originally Posted by Dason
If it makes you feel better I'm actually typically not nervous about Wikipedia. Their math/stats material usually is pretty good! It's always better to look at another resource but I do use wikipedia as a resource more often than you might imagine.
I have always assumed that Wikipedia is so awesome for math/stats stuff basically because: (a) it's not a very controversial area so you don't get people with weird ideas trying to sway your opinion one way or another. plus most people don't really study math at the level where you would want to make weird claims (b) because it deals with (mostly) well-known, verifiable truths. it doesn't take much to read and see quickly whether a certain theorem or claim is justified or not.

all in all, Wikipedia = awesome for math/stats stuff.

don't use it f

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