[R] Strange R squared, possible error

[Bert Gunter]

?summary.lm

The R^2 section  explains that R^2 is computed differently depending
on whether or not an intercept is in the model.

-- Bert

On Wed, Mar 16, 2011 at 12:49 PM, derek <jan.kacaba at gmail.com> wrote:
> k=lm(y~x)
> summary(k)
> returns R^2=0.9994
>
> lm(y~x) is supposed to find coef. a anb b in y=a*x+b
>
> l=lm(y~x+0)
> summary(l)
> returns R^2=0.9998
> lm(y~x+0) is supposed to find coef. a in y=a*x+b while setting b=0
>
> The question is why do I get better R^2, when it should be otherwise?
>
> Im sorry to use the word "MS exel" here, but I verified it in exel and it
> gives:
> R^2=0.9994 when y=a*x+b is used
> R^2=0.99938 when y=a*x+0 is used
>
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-- 
Bert Gunter
Genentech Nonclinical Biostatistics