R help - Nov 2008 - 2^2 factorial design question

Dear R Gurus:

How do you put together a 2^2 (or even 2^k) factorial problem, please?

Since you have 2 levels for A and B, do you put in "A+" and
"A-" as
factors, please?

Thanks,
Edna Bell

Are you looking for expand.grid?

expand.grid(1:2, letters[1:2])

Petr Pikal
petr.pikal at precheza.cz
724008364, 581252140, 581252257


r-help-bounces at r-project.org napsal dne 07.11.2008 01:53:56:
> Dear R Gurus:
> 
> How do you put together a 2^2 (or even 2^k) factorial problem, please?
> 
> Since you have 2 levels for A and B, do you put in "A+" and
"A-" as
> factors, please?
> 
> Thanks,
> Edna Bell
> 
> ______________________________________________
> 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.

On 07-Nov-08 00:53:56, Edna Bell wrote:
> Dear R Gurus:
> 
> How do you put together a 2^2 (or even 2^k) factorial problem, please?
I'm not clear about what you mean here, especially about "put
together"!
Can you describe what you want to end up with in more detail?
> Since you have 2 levels for A and B, do you put in "A+" and
"A-" as
> factors, please?
In any case, I would not use the names "A+" and "A-", since
this
provides too many opportunities for expressions involving these
to be interpreted as arithmetic operations. Better, and safer,
to use names "A1" and "A0", say.

Best wishes,
Ted.
> Thanks,
> Edna Bell
--------------------------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 07-Nov-08                                       Time: 09:51:39
------------------------------ XFMail ------------------------------