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st: RE: Factor Analysis with ordinal and binary variables


From   "Joseph Coveney" <jcoveney@bigplanet.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Factor Analysis with ordinal and binary variables
Date   Tue, 2 Jun 2009 22:38:21 +0900

Stefan Duke wrote:

I have question concerning factor analysis on variables with different
measurement levels.

The questionnaire consists of binary and ordinal variables. If I would
have just binary variables, I would use the tetrachoric correlation
coefficients. For the ordinal I assume approx. normality and then use
the ordinary factor analysis capability.

But what do I do when I have both variables? Is it an option to
construct the variance-covariance matrix by  hand? And what do I take
for the correlation between binary and ordinal?

Maybe is there a model class which takes care of that, that yields
similar outcomes as factor analysis but can deal with such kind of
data (e.g. correspondence analysis).

--------------------------------------------------------------------------------

You can use -polychoric-, a user-written command available from SSC that handles
datasets like yours.  There's a chance that the matrix will not be at least
positive semidefinite, but you can use the -forcepsd- option of -factormat- for
that.

Joseph Coveney


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