[R] A regression problem using dummy variables

Moshe Olshansky m_olshansky at yahoo.com
Wed Jul 2 02:23:48 CEST 2008

Do you have a reason to treat all 3 levels together and not have a separate regression for each level?

--- On Tue, 1/7/08, rlearner309 <unixunix99 at gmail.com> wrote:

> From: rlearner309 <unixunix99 at gmail.com>
> Subject: [R]  A regression problem using dummy variables
> To: r-help at r-project.org
> Received: Tuesday, 1 July, 2008, 11:38 PM
> This is actually more like a Statistics problem:
> I have a dataset with two dummy variables controlling three
> levels.  The
> problem is, one level does not have many observations
> compared with other
> two levels (a couple of data points compared with 1000+
> points on other
> levels).  When I run the regression, the result is bad.  I
> have unbalanced
> SE and VIF.  Does this kind of problem also belong to
> "near sigularity"
> problem?  Does it make any difference if I code the level
> that lacks data
> (0,0) in stead of (0,1)?
> thanks a lot!
> -- 
> View this message in context:
> http://www.nabble.com/A-regression-problem-using-dummy-variables-tp18214377p18214377.html
> Sent from the R help mailing list archive at Nabble.com.
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained,
> reproducible code.

More information about the R-help mailing list