R help - Aug 2012 - Bonferroni correction for multiple correlation tests

Please can someone advise me how I can adjust correlations using
bonferroni's correction? I am doing manny correlation tests as part of an
investigation of the validity/reliability of a psychometric measure.
Help would be so appreciated!
Cheers,
Louise

On Wed, Aug 29, 2012 at 6:23 PM, Louise Cowpertwait
<louisecowpertwait at gmail.com> wrote:
> Please can someone advise me how I can adjust correlations using
bonferroni's correction? I am doing manny correlation tests as part of an
investigation of the validity/reliability of a psychometric measure.
> Help would be so appreciated!
> Cheers,
> Louise
>
The observed correlation is an immutable property of the observed data
and the Bonferroni correction does not change it. Rather, it should be
applied to the p-values of the observed correlations, much as it would
be for any test. Those more statistically savy than I might jump in,
but I don't see why the p-values of, e.g., cor.test() would be
adjusted in a different way than those of t.test().

Consider a similar case for a set of t-tests: you see some data and do
the tests based on the sample means. It doesn't make any sense to
"adjust the mean" of your data, rather you might wish to adjust your
_interpretation_ of calculated p-values to account for multiple
comparisons.

Cheers,
Michael
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On Aug 29, 2012, at 4:23 PM, Louise Cowpertwait wrote:
> Please can someone advise me how I can adjust correlations using  
> bonferroni's correction? I am doing manny correlation tests as part  
> of an investigation of the validity/reliability of a psychometric  
> measure.
> Help would be so appreciated!
?p.adjust

> Cheers,
> Louise
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Alameda, CA, USA

At 00:23 30/08/2012, Louise Cowpertwait wrote:
>Please can someone advise me how I can adjust correlations using 
>bonferroni's correction? I am doing manny correlation tests as part 
>of an investigation of the validity/reliability of a psychometric measure.
Louise, apart from the excellent advice you have already received 
from others on the list I would suggest that if you really, really do 
not have a scientific theory and need go data fishing the correction 
named after Bonferroni is unlikely to be the best approach. There are 
other methods available in p.adjust to which your attention has 
already been drawn.
>Help would be so appreciated!
>Cheers,
>Louise
Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html