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From |
Buzz Burhans <wsb2@cornell.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
re: st: -xtmixed- and random terms nested within fixed treatment terms? |

Date |
Thu, 16 Jun 2005 13:29:39 -0400 |

David, thanks for this. I am looking at it and see if it makes sense to me. I remain unclear as to why the xtmixed does not nest the subjects in the treatment, as I believe both SAS Proc Mixed and S-Plus lme do for a similar design.

I will look closely at this, and some help I solicited off list, and see if it makes sense to me.

Thanks

Buzz Burhans

At 11:32 AM 6/16/2005 -0500, you wrote:

. You said:Suppose I have subjects assigned to treatment with outcomes measured at repeated occasions, and a covariate.This design is a simple one between one within split-plot with a covariate. If we ignore the covariate, the ANOVA design would be, from http://www.ats.ucla.edu/stat/stata/faq/xtmixed.htm: /* spf-2.4 subjects nested in a */ /* between subjects: a */ /* within subjects: b */ use http://www.ats.ucla.edu/stat/stata/examples/kirk/spf2-4, clear /* anova code: */ anova y a / s|a b a*b /, repeated(b) xi3 e.a*e.b xtmixed y _Ia_2 _Ib_2 _Ib_3 _Ib_4 _Ia2Xb2 _Ia2Xb3 _Ia2Xb4 || s: test _Ia_2 test _Ib_2 _Ib_3 _Ib_4 /* scale chi^2 as F-ratio to compare with anova */ display r(chi2)/r(df) test _Ia2Xb2 _Ia2Xb3 _Ia2Xb4 display r(chi2)/r(df) * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

Buzz Burhans wsb2@cornell.edu * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**re: st: -xtmixed- and random terms nested within fixed treatment terms?***From:*David Airey <david.airey@vanderbilt.edu>

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