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Re: st: Two factor anova post test


From   Ángel Rodríguez Laso <angelrlaso@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Two factor anova post test
Date   Wed, 20 Jul 2011 22:54:40 +0200

Sorry I misunderstood which factor was significant.

I cannot give you any advice on carrying out post hoc tests in ANOVA
in Stata, that is one answer to your question, because I haven't done
any. But maybe this link can give you some clues:

http://www.ats.ucla.edu/stat/stata/faq/pairwise.htm

Best regars,

Angel Rodriguez-Laso

2011/7/19 Ricardo Ovaldia <ovaldia@yahoo.com>:
> 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 <angelrlaso@gmail.com> wrote:
>
>> From: Ángel Rodríguez Laso <angelrlaso@gmail.com>
>> Subject: Re: st: Two factor anova post test
>> To: statalist@hsphsun2.harvard.edu
>> 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 <ovaldia@yahoo.com>:
>> > 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
>> >
>> >
>> > *
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>> > *   http://www.ats.ucla.edu/stat/stata/
>> >
>>
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>
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>

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