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st: Polychoric and missing values in correlation matrix

From   Juan Julio Gutierrez <>
Subject   st: Polychoric and missing values in correlation matrix
Date   Thu, 9 Apr 2009 04:50:44 -0700 (PDT)

Dear all

I am using the polychroric command to calculate the correlation matrix of a set of 17 variables ( 8 binary 0-/1 and 9 metric). 

After lenghty calculations STATA shows a matrix  with missing values in the matrix, mostly between metric and binary variables. 4 metric variables have missing values correlations with binary variables. 

The results window show these messages. In red: 

could not calculate numerical derivatives

missing values encountered

initial values not feasible

too few quotes

no variables defined

And in green: 

numerical derivatives are approximate

nearby values are missing

Do you have an idea why am I facing these results?

How can I assure that the corr. matrix is positive defined?

Do you know if using R poly command would dela with the missing values? . 

Thank you 

Juan Julio

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