[R] regression function for categorical predictor data

[Joshua Wiley]

Hi,

If your predictor variable is categorical than it should be converted
to a factor.  If it is continuous or being treated as such, you do not
need to.  It is generally quite easy to do:

varname <- factor(varname)

or if it is in a data frame

yourdf$varname <- factor(yourdf$varname)

Cheers,

Josh

On Thu, Sep 9, 2010 at 8:09 AM, karena <dr.jzhou at gmail.com> wrote:
>
> Hi, thank you very much for the help.
> one more quick question: is that, my predictor variable should be coded as
> 'factor' when using either 'lm' or 'glm'?
>
> sincerely,
>
> karena
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/