Keeping in mind that it's a textbook, I suspect that the authors were just
trying to keep the numbers of numbers small. All replicates within a cell
having the same value is rather rare in practice.
However, the greater question appears to be that of violating the
assumption of homogeneity of variance. ANOVA is robust against such
violations when the cell sizes are equal...
WBW
__________________________________________________________________________
William B. Ware, Professor and Chair Educational Psychology,
CB# 3500 Measurement, and Evaluation
University of North Carolina PHONE (919)-962-7848
Chapel Hill, NC 27599-3500 FAX: (919)-962-1533
http://www.unc.edu/~wbware/ EMAIL: [EMAIL PROTECTED]
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On Wed, 13 Dec 2000, 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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