I have changed a few lines of code in polychoric.ado so that it returns a
missing value in the correlation matrix when the likelihood maximization
procedure breaks down (in my experience, because of the flat likelihoods,
or because it hits the boundary of the parameter space when the absolute
value of the correlation is 1). The current version of the ado-file is
1.4.3.
Bug reports are welcome. My longer term plans are to write the analytical
derivatives, but it is not going to happen very soon, I am afraid :((.
--- Stas Kolenikov
-- Ph.D. student in Statistics at UNC-Chapel Hill
- http://stas.kolenikov.name -- [email protected]
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