though you have not indicated the kind of data you are referring to ... nor
treatments, etc. ... if the ns are decent in each group ... i would
seriously question the design ... or data collection process ... IF you had
NO within group variance AT all ... in ANY group ...
when you collect data in a design like you refer to, you have to ask
yourself: how is it possible that i can "test" a within group ... with some
data collection instrument ... and have each and every value in the group
be identical?
THAT i think is a more serious problem
At 12:24 AM 12/13/00 +0000, Gene Gallagher wrote:
>The textbook I'm using this semester presents a 2-factor ANOVA problem
>(3 levels of each factor) in which two of the 9 groups have zero
>variance (identical observations for two replicates). Levene's test
>indicates significant departure from homoscedasticity (this may not be
>known to the authors of the text who provide the solution as if there
>were no problems with homogeneity of variance). Is there ever a case
>when you can trust the ANOVA results despite violations of
>homoscedasticity like this? Obviously, no transformation is appropriate
>and the non-parametric ANOVAs aren't good at handling interaction
>effects (at least not Friedman).
>
>--
>Eugene D. Gallagher
>ECOS, UMASS/Boston
>
>
>Sent via Deja.com
>http://www.deja.com/
>
>
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dennis roberts, educational psychology
penn state university, 208 cedar building
university park, pa USA 16802 ... AC 8148632401
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