Message-ID: <CAAmySGMnX6q=RHqYqe2Jr7qCYbA6UXVff-3kY-dpjFKQ8mO4vw@mail.gmail.com>
Date: 2011-11-15T05:11:48Z
From: R. Michael Weylandt
Subject: Question about linear regression in R
In-Reply-To: <CAMPud10yg-F9yt04E5E9_s8QKFNiQ+C=hDyH5Mrvp-YMjMPfqQ@mail.gmail.com>
What exactly is it that's worrying you? It's a problematic regression
for a few reasons, but ultimately it seems pretty ok, though I'd be
ever so slightly worried about the R^2 value being misinterpreted.
Michael
On Mon, Nov 14, 2011 at 10:49 PM, Miles Yang <miles2yang at gmail.com> wrote:
> Hi all,
> I wrote a r program as below:
>
> x <- 1:10
> y <- c(3,3,3,3,3,3,3,3,3,3)
>
> fit <- lm(log(y) ~ x)
> summary(fit)
>
> And I expect to get some error message from R, because "y" is constant.
> But, I got the message as below:
>
>> summary(fit)
>
> Call:
> lm(formula = log(y) ~ x)
>
> Residuals:
> ? ? ? Min ? ? ? ? 1Q ? ? Median ? ? ? ? 3Q ? ? ? ?Max
> -6.802e-17 -3.933e-17 -1.063e-17 ?1.807e-17 ?1.530e-16
>
> Coefficients:
> ? ? ? ? ? ? ?Estimate Std. Error ? ?t value Pr(>|t|)
> (Intercept) ?1.099e+00 ?4.569e-17 ?2.404e+16 ? <2e-16 ***
> x ? ? ? ? ? -1.275e-17 ?7.364e-18 -1.732e+00 ? ?0.122
> ---
> Signif. codes: ?0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
>
> Residual standard error: 6.688e-17 on 8 degrees of freedom
> Multiple R-squared: 0.5794, Adjusted R-squared: 0.5269
> F-statistic: 11.02 on 1 and 8 DF, ?p-value: 0.01054
>
> How could this be possible?
> Did I missing something in my R code?
>
> Best,
> Miles
> --
> ??????????????????
> Miles Yang
> Mobile?+61-411-985-538
> E-mail?miles2yang at gmail.com
> ??????????????????
>
> ? ? ? ?[[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.
>
>