Bonferroni

Glenn Rosen gdr at dyslab.bih.harvard.edu
Fri Jul 1 11:20:42 EST 1994


In article <pdoyle-010794095237 at 129.194.99.25>, pdoyle at medsun.unige.ch
(Patrick Doyle) wrote:

> Can anyone tell me when the bonferroni adjustment to samples of 2 groups
> should or should not be carried out.For instance,if I have several areas in
> the brain for which I have taken 6 bilalteral measurements and compare them
> to the same number of measurements and same areas from a separate tested
> group of rats - 
> should I first ANOVA then t test with a bonferroni or should I compare the
> weighted totals and then specifically test the areas by the t test -simple
> unpaired .Is it serious to consider the individual areas as being different
> and therefore assuming the various areas as being sampled from an
> heterogeneous tissue?Does this therefore constitute multiple sampling or
> not?
> Thanks for any comments.

I'm not sure I follow exactly what you want to do, but is sounds like you
can set up a 2 within, 1 between ANOVA to handle the analysis. First, you
must consider the measures of the values in the right and left hemispheres
from the same subject as a repeated measure. In addition, each of the 6
values from the subject should be as a repeated measure. This is true
because the measures are inherently correlated. You can then use your two
separate testing cohorts as a between independent measure. 

This analysis has the advantage of allowing you to determine (quite
sensitively) asymmetry, relationships between the values from different
brain regions, as well as determining whether there is a difference between
the two cohorts of subjects. There is no need for Bonferroni adjustments.

Hope this helps.

Glenn Rosen



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