[R] How to do a PCA with ordered variables?

Hi, I want to do a pca using a set of variables which are ordered. I have used the dudi.mix method from the ade4 package, but when I do the $index it shows me that R has considered my variables as quantitative. What should I do? -- View this message in context:

Re: [R] How to do a PCA with ordered variables?

P. Branco wrote: I have used the dudi.mix method from the ade4 package, but when I do the $index it shows me that R has considered my variables as quantitative. What should I do? You should make sure that they are encoded as ordered factors, which has nothing to do with ade4's

Re: [R] How to do a PCA with ordered variables?

If you are really serious about your variables being ordinal, you should analyze them using polychoric correlations. See polycor package by John Fox. On Thu, Sep 17, 2009 at 10:52 AM, Mark Difford mark_diff...@yahoo.co.uk wrote: I have used the dudi.mix method from the ade4 package, but when I