Re: [R] A regression problem using dummy variables

From: rlearner309 <unixunix99_at_gmail.com>
Date: Tue, 01 Jul 2008 22:01:33 -0700 (PDT)

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@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:
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>> Sent from the R help mailing list archive at Nabble.com.
>>
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> 
> ______________________________________________
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> 
> 

-- 
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Received on Wed 02 Jul 2008 - 08:12:14 GMT

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