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RE: st: Anova with not variance homogeneity


From   "Allan Reese (Cefas)" <allan.reese@cefas.co.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Anova with not variance homogeneity
Date   Thu, 4 Oct 2007 11:39:17 +0100

You need to ask in such circumstances what is being tested.  ANOVA is, implicitly, a comparison of location parameters but is often misreported as showing "difference" or "no difference" without specifying in what.

Approaches would include non-parametric anova (comparing medians rather than means), variance-stabilizing transformations, and GLMs which do not assume the random terms are "normal with equal variance".
Allan   

------------------------------

Date: Wed, 03 Oct 2007 15:49:18 +0200.  Rachele Capocchi <rachele.capocchi@arsanita.toscana.it> asked:
 
Can anybody help me to do Anova test if there is difference on the 3 groups' means with Stata, 
considering that the variances of 3 groups are not homogeneity ?


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