[R] A regression problem using dummy variables

[rlearner309]

Yes.  Because the slopes are supposed to be the same.
Level shifts are needed to be modeled.


Moshe Olshansky-2 wrote:
> 
> 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!
>> -- 
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>> 
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> 
> ______________________________________________
> R-help at r-project.org mailing list
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> 
> 

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