Maria:
the answer to your question is reported in Example 1 of -sureg- entry, Stata .pf manual.
If you had the chance to get a copy of http://www.stata.com/bookstore/microeconometrics-stata/., please see also pages 163-169.
the answer to your question is reported in Example 1 of -sureg- entry, Stata .pf manual.
If you had the chance to get a copy of http://www.stata.com/bookstore/microeconometrics-stata/., please see also pages 163-169.
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