R help - Jul 2009 - Correlation question (from a newbie)

Hi R-users,

Was wondering if there is a way to quickly compute correlations between
continuous variables grouped by some categorical variables?

What function do I use?

Thanks much in advance.

Regards,
Santosh

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On Jul 14, 2009, at 10:34 PM, Santosh wrote:
> Hi R-users,
>
> Was wondering if there is a way to quickly compute correlations  
> between
> continuous variables grouped by some categorical variables?
>
> What function do I use?
>
?tapply
?by
> Thanks much in advance.
>
> Regards,
> Santosh
>
> 	[[alternative HTML version deleted]]

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

Dear R-users..

I hope the following scenario is more explanatory of my question..

Continuous variables: AGE, WEIGHT, HEIGHT
Categorical variables: Group, Sex, Race
I would like to find a correlation between WEIGHT and AGE, grouped by
"Group","Sex", and "Race".

Is the following formula correct?
tapply(dat$WEIGHT,
by=list(dat$AGE,as.factor(dat$Group),as.factor(dat$EX),as.factor(dat$RACE)),cor)


Thanks,
Santosh

On Tue, Jul 14, 2009 at 7:34 PM, Santosh <santosh2005@gmail.com> wrote:
> Hi R-users,
>
> Was wondering if there is a way to quickly compute correlations between
> continuous variables grouped by some categorical variables?
>
> What function do I use?
>
> Thanks much in advance.
>
> Regards,
> Santosh
>
	[[alternative HTML version deleted]]