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

[Stas Kolenikov]

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_difford at yahoo.co.uk> 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 dudi.mix().
>
> ##
> ?ordered
>
> Mark.
>
>
>
> P.Branco wrote:
>>
>> 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?
>>
>
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-- 
Stas Kolenikov, also found at http://stas.kolenikov.name
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