[R] About the covariant

[David Winsemius]

On Jun 27, 2011, at 10:02 PM, Lao Meng wrote:

> Hi all,I have some questions about the covariants of regression.
>
> My target: To explore the trend of CD4 level through a period of time.
>
> Response variable: CD4 count
> Explanatory variable:time
>
> Also, the demology information is available,such as  
> gender,occupation,income
> level...
>
> Q1,Are these variables of demology information called covariant?
> Q2,How can I correct the impact of "covariant" so that I can get the
> "corrected result" of CD4's change through the time period?
> Q3,How to treat the covariants in regression?I've looked up to many  
> papers
> of R on regression,which treat the covariant in the same
>
> way as the Explanatory variable,like following:
> lm(CD4 ~ time + gender + income)

Yes that seems pretty standard practice. It does, of course, force the  
relationships to a) be linear and b) means that a single slope and  
intercept are estimated for each variable, neither of a} or b}  
assumptions may be true.
>
>> From above expression of regression,it's obvious that the response  
>> variables
> and covariants are treated the same way,

In what sense are you making that claim? True they are both numeric,  
but what else are you saying?

-- 
David

> but acturally
>
> they are totally different.
>
>
>
> Thanks for your help.
>
> My best.
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.

David Winsemius, MD
West Hartford, CT