Matrix of dummy variables from a factor

Good point. Probably not for any subsequent use in R. But, I work in an
org that uses SAS, HLM, SPSS, among others. As a part of our control
processes at times we replicate analyses in different software programs.
For instance, we will replicate lmer functions using HLM. But, HLM
requires a matrix of dummy variables. So, I have used R to create this
matrix  for use in another software package that does need it.

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Berton Gunter
Sent: Tuesday, December 06, 2005 4:27 PM
To: 'Liaw, Andy'; 'Charles H. Franklin'; r-help at stat.math.ethz.ch
Subject: Re: [R] Matrix of dummy variables from a factor

But note: There are (almost?) no situations in R where the dummy
variables coding is needed. The coding is (almost?) always handled
properly by the modeling functions themselves.

Question: Can someone provide a "straightforward" example where the
dummy variable coding **is** explicitly needed?

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA

"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box