[R] A quick question about lm()

[(Ted Harding)]

On 07-Jul-08 13:38:12, rlearner309 wrote:
> 
> I have a simple regression using lm().
> If I just want to check the coefficient, I can use summary(lm())$coef;
> if I need the standard error, I can use summary(lm())$s, if I need
> the residuals, I can use summary(lm())$res.  OK.  How can I get the
> R-squares and Adjusted R-squares using $...?
> Is there a function, like objects(), that can show all the references
> for values?
> 
> Thanks a lot!

A useful function is str(), which displays the components of an object.
Example:

> X<-rnorm(10);Y<-rnorm(10)
> LM<-lm(Y~X)
> sumLM<-summary(LM)
> str(sumLM)
List of 11
 $ call         : language lm(formula = Y ~ X)
 $ terms        :Classes 'terms', 'formula' length 3 Y ~ X
  .. ..- attr(*, "variables")= language list(Y, X)
  .. ..- attr(*, "factors")= int [1:2, 1] 0 1
  .. .. ..- attr(*, "dimnames")=List of 2
  .. .. .. ..$ : chr [1:2] "Y" "X"
  .. .. .. ..$ : chr "X"
  .. ..- attr(*, "term.labels")= chr "X"
  .. ..- attr(*, "order")= int 1
  .. ..- attr(*, "intercept")= int 1
  .. ..- attr(*, "response")= int 1
  .. ..- attr(*, ".Environment")=<R_GlobalEnv> 
  .. ..- attr(*, "predvars")= language list(Y, X)
  .. ..- attr(*, "dataClasses")= Named chr [1:2] "numeric" "numeric"
  .. .. ..- attr(*, "names")= chr [1:2] "Y" "X"
 $ residuals    : Named num [1:10]  0.086 -0.345 -1.542 -0.168 -0.894 ...
  ..- attr(*, "names")= chr [1:10] "1" "2" "3" "4" ...
 $ coefficients : num [1:2, 1:4]  0.270 -0.289  0.387  0.321  0.699 ...
  ..- attr(*, "dimnames")=List of 2
  .. ..$ : chr [1:2] "(Intercept)" "X"
  .. ..$ : chr [1:4] "Estimate" "Std. Error" "t value" "Pr(>|t|)"
 $ aliased      : Named logi [1:2] FALSE FALSE
  ..- attr(*, "names")= chr [1:2] "(Intercept)" "X"
 $ sigma        : num 1.06
 $ df           : int [1:3] 2 8 2
 $ r.squared    : num 0.0921
 $ adj.r.squared: num -0.0213
 $ fstatistic   : Named num [1:3] 0.812 1.000 8.000
  ..- attr(*, "names")= chr [1:3] "value" "numdf" "dendf"
 $ cov.unscaled : num [1:2, 1:2]  0.1322 -0.0541 -0.0541  0.0912
  ..- attr(*, "dimnames")=List of 2
  .. ..$ : chr [1:2] "(Intercept)" "X"
  .. ..$ : chr [1:2] "(Intercept)" "X"
 - attr(*, "class")= chr "summary.lm"


>From which you can see that the R-squared and Adjusted R-squared
are available as summary(LM)$r.squared and summary(LM)$adj.r.squared

Hoping this helps,
Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 07-Jul-08                                       Time: 15:28:19
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