[R] Crawley's book on S-Plus and one strangeness

[Douglas Bates]

matej at ceplovi.cz (Matej Cepl) writes:

> I have got to my hands an excellent book by Michael J. Crawley
> ``Statistical Computing: An Introduction to Data Analysis using
> S-Plus'' (John Wiley & Sons, Ltd, ISBN 0-471-56040-5). Its beauty
> for me is in the fact, that it is more of ``An Introduction to
> Data Analysis'' than ``using S-Plus'', but I guess that it may be
> of interest for many others.

> Most of the examples in the book are however taken from S-Plus
> and using datasets provided with it. Is there anywhere a copy of
> these datasets available for R?

Can you be more specific?  Which datasets?

> And one small question aside: I was very much surprised (in this
> book as well as on this list) how many times people use
> sqrt(var(x)) when what they want to say (IMHO) is sd(x). Is it
> just a macho way to show that I understand more complicated
> things, or is there any real difference between the two?

The var function was available in S long before the sd function was
introduced and many 'old-timers' instinctively use sqrt(var(x)) rather
than sd(x).  The sd function ends up calling sqrt(var(x, na.rm =
na.rm)) when argument x is a vector.