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From |
graupel75@gmail.com |

To |
Statalist <statalist@hsphsun2.harvard.edu> |

Subject |
Re: st: Prediction at the 'mean' of a categorical- xi3? |

Date |
Thu, 14 Mar 2013 11:59:08 +0800 |

JVerkuilen writes: >Nothing in the math says you can't center dummy variables; I do it all >the time using the usual Stata commands to make the intercept a >meaningful number. Effects coding in some sense does this in the >classic ANOVA setup but won't in a general regression due to the lack >of orthogonality. I've used both -xi3- center option and generated the mean-centered var by hand, and run the regression with this new var, but the log lik and AIC/BIC are quite different indicating that more than just the ref category has changed... so I must be confused. Let's say I have a categorical (levels 1 to 6), do I then estimate with the mean-centered value as a continuous var, and predict at 3.5? This doesn't make so much sense as it would assume the steps between levels are equivalent; I've looked in both Agressi and Long's Stata book without success- thanks! Andrew ______________________________________________ Epidemiologist Centre for Infectious Disease Epidemiology Research (CIDER) Saw Swee Hock School of Public Health National University of Singapore * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Prediction at the 'mean' of a categorical- xi3?***From:*David Hoaglin <dchoaglin@gmail.com>

**Re: st: Prediction at the 'mean' of a categorical- xi3?***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

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