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st: Warning on mlogit
From
Maria Sokolova <[email protected]>
To
[email protected]
Subject
st: Warning on mlogit
Date
Wed, 10 Jul 2013 18:43:04 +0200
Dear all,
Please give some advice on the following. All regression worked for
the full sample of several years. When I restrict the sample for 3
years only, the "Warning: variance matrix is nonsymmetric or highly
singular" appears. I read the thread that was here several years ago
(http://www.stata.com/statalist/archive/2008-01/msg00980.html), but do
not really understand how it is applicable for me....
Mlogit has three choices and the clusters are for year-product (also
tried month-product, same thing). Choices are about 30% 55% 15% for a
given year.
the point is, that even the mlogit on the constant shows this warning...
the simplest (shortest) example is
mlogit pt dtime*, b(2) robust cluster(cluster1)
pt - three choices unordered
dtime - monthly dummies..
What can I do about this Warning?
Thanks again for your help,
Best,
Maria
--
- - - - -
Maria Sokolova
PhD student International Economics
The Graduate Institute of International and Development Studies
[email protected]
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