[R] factor analysis

[John Fox]

Dear Allan,

I assume that the categorical data are ordinal. There are methods for
factor analyzing ordinal data (e.g., using polychoric correlations) and
mixed ordinal and interval data, but as far as I know, these aren't
implemented in R.

John

On Thu, 13 May 2004 18:32:11 +0200
 allan clark <allan at stats.uct.ac.za> wrote:
> hi all
> 
> this is a stats question.
> 
> when undertaking factor analysis should the variables included always
> be
> continiuos random variables? could one include categorical data? e.g
> some survey type data
> 
> my gut feeling is that one should not include categorical type data
> since factor analysis is based on the eigenanalysis of the
> correlation
> matrix of a group of variables. The introduction of categorical data
> into a data set might "mess up" the corelation matrix.
> 
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--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox/