While following the suggestion in the manual "An Introduction to R" to 
begin with Appendix A, I ran into the problem shown below about 3/4 of 
the way down the 1st page of App. A.

After using the function /attach/, I did not get visible columns in the 
data frame as indicated but the rather puzzling message emphasized below.

I am running R version 3.1.0 (2014-04-10) using Windows XP.  Thanks in 
advance for your help.

> > x<-1:20
> > w<-1+sqrt(x)/2
> > dummy<-data.frame(x=x, y=x+rnorm(x)*w)
> > dummy
>     x         y
> 1   1  2.885347
> ...
> > fm<- lm(y ~ x, data=dummy)
> > summary(fm)
>
> Call:
> ...
> > fm1<- lm(y ~ x, data=dummy,weight=1/w^2)
> > summary(fm1)
>
> Call:
> ...
> > attach(dummy)
> *_The following object is masked _by_ .GlobalEnv:
>
>     x_**_
> _*

-- 
/Stephen A Meskin/, PhD, FSA, MAAA
Adjunct Assistant Professor of Mathematics, UMBC

**//

	[[alternative HTML version deleted]]

