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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Berton Gunter Sent: Tuesday, December 06, 2005 4:27 PM To: 'Liaw, Andy'; 'Charles H. Franklin'; r-help@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 > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Liaw, Andy > Sent: Tuesday, December 06, 2005 12:30 PM > To: 'Charles H. Franklin'; r-help@stat.math.ethz.ch > Subject: Re: [R] Matrix of dummy variables from a factor > > See ?model.matrix. > > HTH, > Andy > > From: Charles H. Franklin > > > > What is a simple way to convert a factor into a matrix of dummy > > variables? > > > > fm<-lm(y~f) > > > > where f is a factor takes care of this in the estimation. > I'd like to > > save the result of expanding f into a matrix for later use. > > > > Thanks. > > > > Charles > > > > -- > > > > > > Charles H. Franklin > > Professor, Political Science > > University of Wisconsin, Madison > > [EMAIL PROTECTED] > > [EMAIL PROTECTED] > > 608-263-2022 (voice) > > 608-265-2663 (fax) > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html