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From |
"Sam Norton" <samjnorton@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: is there a -regress- command equivalent to the pair matched ttest? |

Date |
Tue, 9 Dec 2008 15:12:14 +0000 |

Jose Maria You can, if you really want to, use -xtmixed-. Phil Enders presentation at the West Coast Stata Users Group meeting in 2007 gives an example of how to use -xtmixed- to estimate a RM-ANOVA. Since ANOVA is based on deviations from the grand mean -xi3- (available from SSC) is needed to create effect coded variables. http://www.stata.com/meeting/wcsug07/repeated_anova.pdf -- Sam Norton samjnorton@gmail.com Research Student Centre for Lifespan & Chronic Illness Research University of Hertfordshire 2008/12/9 David Airey <david.airey@vanderbilt.edu> > > A paired ttest is equivalent to a repeated measures ANOVA with two levels to the repeated factor. You can see the regression equivalent below. > > webuse fuel, clear > list, clean > ttest mpg1 == mpg2 > local t = r(t) > generate subject = _n > list, clean > reshape long mpg, i(subject) j(repeat) > list, clean > anova mpg repeat subject > anova, regress > test repeat > local F = r(F) > display `F' "=" `t'^2 > xi: regress mpg i.repeat i.subject > > > > On Dec 8, 2008, at 7:05 PM, josemaria wrote: > >> Dear Statalisters: >> I am not sure whether it makes sense or not, but is there a sort of -regress- command that allows to conduct a pair-matched -ttest-, but with other independent variables? >> I tried using -xtmixed-, but the result is not the same. >> A contrived data set could be: >> matching_identification outcome ocasion variable_not_matched >> 1 1 1 0 >> 1 2 2 0 >> 2 3 1 0 >> 2 5 2 1 >> 3 2 1 0 >> 3 4 2 1 >> 4 6 1 1 >> 4 5 2 1 >> To perform the pair-matched ttest it is necessary to -reshape- and to use -ttest outcome1==outcome2-, losing the independent variable_not_matched. >> Thank for any orientation. >> Regards, >> José Maria >> >> Jose Maria Pacheco de Souza, Professor Titular (aposentado) >> Departamento de Epidemiologia/Faculdade de Saude Publica, USP >> Av. Dr. Arnaldo, 715 >> 01246-904 - S. Paulo/SP - Brasil >> fones (11)3061-7747; (11)3768-8612 >> fax (11)3714-2403 >> www.fsp.usp.br/~jmpsouza >> * >> * 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/ > > > * > * 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/ * * 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/

**Follow-Ups**:**Re: st: is there a -regress- command equivalent to the pair matched ttest?***From:*David Airey <david.airey@Vanderbilt.Edu>

**References**:**st: new package -byhist- on SSC***From:*"Austin Nichols" <austinnichols@gmail.com>

**st: is there a -regress- command equivalent to the pair matched ttest?***From:*"josemaria" <jmpsouza@usp.br>

**Re: st: is there a -regress- command equivalent to the pair matched ttest?***From:*David Airey <david.airey@vanderbilt.edu>

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