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From |
Maarten Buis <[email protected]> |

To |
[email protected] |

Subject |
Re: st: How to constraint the sum of the coefficients to zero for a factor variable. |

Date |
Fri, 5 Aug 2011 14:19:42 +0200 |

On Fri, Aug 5, 2011 at 1:28 PM, Sam Brilleman wrote: > Does anyone know how to change the constraint on the coefficients for 'var4' > so that the sum of the coefficients is zero (i.e. sum(b4i) = 0) rather than > treating one of the factor levels as a reference category (i.e. b4i = 0 for > some given i). Note that the latter is the standard parameter constraint > used by STATA's estimation commands. I don't know of a way to do this in Stata's factor variable notation. You can however create the necesary variables using -xi3-, where they are called "effect coding", see -findit xi3-. Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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