R help - Aug 2008 - Correlation dichotomous factor, continous (numerical) and ordered factor

Hello R-User!

I appologise in advance if this should also go into statistics but I am
presently puzzled.
I have a data.frame (about 300 rows and about 80 variables) and my variables
are dichotomous factors, continuous (numerical) and ordered factors.

I would like to calculate the linear correlation between every pair of my
variables, because I would like to perform a logistic regression (glm())
without the correlation between variables.

I thought I could use for the continous (numerical) and ordered factor a
spearman correlation that is using the ranks.

But I thought also that I have to use a contingency table for the
dichotomous factors. 

I read also that it is possible to use a point-biserial correlation to
calculate the correlation between dichotomous and continuous variables.

Now I am confused what I should use to calculate the correlation using all
my variables and how I could do that in R.
Is it possible with cor(), rcorr(), cormat() or other R-functions using one
of the available correlation-coefficients.

I would be very happy if somebody could enlighten my darkness.

Many thanks in advance.

B.


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Hi Birgitle,
>> ... my variables are dichotomous factors, continuous (numerical) and
>> ordered factors. ...
>> Now I am confused what I should use to calculate the correlation using
>> all my variables
>> and how I could do that in R.
Professor Fox's package polycor will do this for you in a very nice way.

Regards, Mark.


Birgitle wrote:
> 
> Hello R-User!
> 
> I appologise in advance if this should also go into statistics but I am
> presently puzzled.
> I have a data.frame (about 300 rows and about 80 variables) and my
> variables are dichotomous factors, continuous (numerical) and ordered
> factors.
> 
> I would like to calculate the linear correlation between every pair of my
> variables, because I would like to perform a logistic regression (glm())
> without the correlation between variables.
> 
> I thought I could use for the continous (numerical) and ordered factor a
> spearman correlation that is using the ranks.
> 
> But I thought also that I have to use a contingency table for the
> dichotomous factors. 
> 
> I read also that it is possible to use a point-biserial correlation to
> calculate the correlation between dichotomous and continuous variables.
> 
> Now I am confused what I should use to calculate the correlation using all
> my variables and how I could do that in R.
> Is it possible with cor(), rcorr(), cormat() or other R-functions using
> one of the available correlation-coefficients.
> 
> I would be very happy if somebody could enlighten my darkness.
> 
> Many thanks in advance.
> 
> B.
> 
> 
-- 
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