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st: exploratory factor analysis with dichotomous and continuous data


From   Frauke Rudolf <FRAUKE.RUDOLF@ki.au.dk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: exploratory factor analysis with dichotomous and continuous data
Date   Wed, 21 Nov 2012 10:37:37 +0000

Hi,
I am trying to run an exploratory factor analysis with both dichotomous and continuous data using the polychoric command.
However, when I try to run it, I get the following error message:
"numerical derivatives are approximate
nearby values are missing
could not calculate numerical derivatives
missing values encountered
numerical derivatives are approximate
nearby values are missing
could not calculate numerical derivatives
missing values encountered"

I found some useful threads on the net, so now I know why I get the message; It is due to one of the dichotomous variables having 0 observations in one of the 2x2 tables:
haemoptysi |         cough
         s |         1          2 |     Total
-----------+----------------------+----------
         1 |       168          0 |       168 
         2 |       896         53 |       949 
-----------+----------------------+----------
     Total |     1,064         53 |     1,117 

What I could not find, was a solution on, how to deal with this in order to be able to run an EFA.
I hope you can help me with this.

Frauke


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