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R: st: Two factor anova post test
From
"Carlo Lazzaro" <[email protected]>
To
<[email protected]>
Subject
R: st: Two factor anova post test
Date
Tue, 19 Jul 2011 13:05:43 +0200
Dear Ricardo,
why not performing a one-way ANOVA on the significant factor (race) and, if
appropriate, perform a multiple comparison with correction?
I agree with Angel that the risk of inflating Type 1 error is probably
negligible. Anyway, you can explore in depth this issue with different
critical values.
Kindest Regards,
Carlo
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Ricardo Ovaldia
Inviato: martedì 19 luglio 2011 12.19
A: [email protected]
Oggetto: Re: st: Two factor anova post test
Thank you Angel. The term that is significant is race, with three levels,
therefore I am not completely sure which means are different, and I do not
understand how to use -test-, or even if that is the correct way to compare
them.
Thank you,
Ricardo.
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
--- On Mon, 7/18/11, Ángel Rodríguez Laso <[email protected]> wrote:
> From: Ángel Rodríguez Laso <[email protected]>
> Subject: Re: st: Two factor anova post test
> To: [email protected]
> Date: Monday, July 18, 2011, 4:05 PM
> Dear Ricardo;
>
> If you were having many factors and many interactions, you
> should be
> worried about and incresed alpha error level for the
> F-test, but with
> 2 factors I doubt this is a problem. Moreover, your p level
> for the
> significance of sex is far away from the conventional 0.05,
> while the
> interaction sex*race is non-significant. Therefore you can
> conclude
> that there is a significant difference only between sexes.
> Because
> there are only two levels, there is no need to carry out
> any posthoc
> test like Scheffe, because you already know which means are
> different,
> those of men and women.
>
> Best regards,
>
> Angel Rodriguez-Laso
>
> 2011/7/18 Ricardo Ovaldia <[email protected]>:
> > Hello,
> >
> > I performed a two factor ANOVA; one factor (sex) has 2
> levels and the other factor (race) has 3 levels. The
> interaction term is not significant but one of the factors,
> race, is (p=0.0004). How can I determine which means are
> different while maintaining the experiment wise type I error
> rate.
> >
> > If I had only one factor, I could use -oneway- and
> then use, for example, scheffe for multiple comparisons. But
> not sure what to do with two factors.
> >
> > Thank you in advance,
> > Ricardo
> >
> > Ricardo Ovaldia, MS
> > Statistician
> > Oklahoma City, OK
> >
> >
> > *
> > * 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/
>
*
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