re: st: Repeated measures ANOVA with mutually dependent variables

[David Airey <david.airey@Vanderbilt.Edu>]

.

> I have the following subtracted electrophysiological data from  
> three conditions
> a-b, a-c, and b-c, and I would like to know if it is feasible to  
> introduce in
> the same repeated measures ANOVA these subtracted variables since  
> they are
> mutually dependent? or if doing so I am violating the ANOVA�s  
> assumptions.
> Please, provide me also with some references where I can read about  
> this issue.
>
> I would extremely appreciate your valuable help,
>
> Selene Cansino
Using completely determined regressors in regression can cause it to  
fail. Suppose you make three 0,1 indicator variables for three  
groups, and then use all of them instead of two of them in a  
regression. It will fail if you use all three. You should use two and  
leave one out for the comparison group. Run your model and see! As  
for assumptions, use diagnostic plots and tests to establish if the  
assumptions have been met, once you establish the model doesn't fail  
because of a singularity.

-Dave
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