[R] coding for categorical variables with unequal observations
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Apr 4 07:40:03 CEST 2008
I think you need to do some background reading. R does this automatically
for you, and offers many options for how it is done. (That you have asked
suggests you have missed that.)
The account by Bill Venables in chapter 6 of MASS (the book, see the R
FAQ) is regarded as the most comprehensive available.
On Thu, 3 Apr 2008, Tanya Yatsunenko wrote:
> Also, since I just started to use R, I have trouble generating and
> understanding some of the codes, especially choosing the correct ones.
> On Thu, Apr 3, 2008 at 3:54 PM, Tanya Yatsunenko <yata25 at gmail.com> wrote:
>> I am doing multiple regression, and have several X variables that are
>> I read that I can use dummy or contrast codes for that, but are there any
>> special rules when there're unequal #observations in each groups (4 females
>> vs 7 males in a "gender" variable)?
>> Also, can R generate these codes for me?
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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