[R] factor analysis

[allan clark]

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.