Principal Components Analysis on factor data.

["Augusto Cesar H. Dantas" <augusto@lps.ufrj.br>]

        Dear all,
        
        does anybody know a way to extract components in a 
'YES/NO/DON'T KNOW' data? The data I have consists of answers to a 
survey, and I would like to analyse the relevance of the different questions.
(note that a simple transformation to 1/0/-1 data would result in real 
number components; I would like a kind of ''binary PCA'')

        Thanks in advance,
        Augusto. 

-- 
Augusto Cesar Heluy Dantas
D.Sc. Student at COPPE/UFRJ
Rio de Janeiro, Brazil