
On Nov 16, 2009, at 2:53 PM, Jack Luo wrote:

> David,
>
> Thanks for your reply. Since I am kinda new to this forum, could you  
> please advise me on where to read those questions in R-help?

http://search.r-project.org/nmz.html

http://search.r-project.org/cgi-bin/namazu.cgi?query=%22ordered+factors%22&max=100&result=normal&sort=score&idxname=functions&idxname=Rhelp08&idxname=views

> In addition, I did not pay much attention to the na.action, probably  
> I should use na.action = na.omit instead of na.pass.
>

Or just accept the default.

> -Jack
>
> On Mon, Nov 16, 2009 at 2:32 PM, David Winsemius <dwinsemius@comcast.net 
> > wrote:
>
> On Nov 16, 2009, at 2:22 PM, Jack Luo wrote:
>
> Hi,
>
> I am trying to fit a logistic regression using glm, but my explanatory
> variables are of mixed type: some are numeric, some are ordinal,  
> some are
> categorical, say
>
> If x1 is numeric, x2 is ordinal, x3 is categorical, is the following  
> formula
> OK?
>
> The formula's certainly "OK". What may be non-OK will be your  
> understanding of the output. The default handling of ordinal factors  
> is a common source of questions to R-help, so read up first.
>
> *model <- glm(y~x1+x2+x3, family=binomial(link="logit"),  
> na.action=na.pass)*
>
> Why have you chosen that na.action option?
>
> -- 
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT


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