[R] P values

[Frank E Harrell Jr]

On 05/11/2010 04:50 PM, Bert Gunter wrote:
> Inline below.
>
> -- Bert

Bert - I disagree with you.  You have understated the problems with 
P-values  :-)

Frank
>
>
> Bert Gunter
> Genentech Nonclinical Statistics
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of Greg Snow
> Sent: Tuesday, May 11, 2010 2:37 PM
> To: Bak Kuss; murdoch.duncan at gmail.com; jorismeys at gmail.com
> Cc: R-help at r-project.org
> Subject: Re: [R] P values
>
> Bak,
>
> ...
>
> "  Small p-values indicate a hypothesis and data that are not very
> consistent and for small enough p-values we would rather disbelieve the
> hypothesis (though it may still be theoretically possible). "
>
>
> This is false.
>
> It is only true when the hypotheses are prespecified (not derived from
> looking at the data first), when there's only one being tested (not,say,
> 10,000), etc. etc.
>
> (Incidentally, "small enough" is not meaningful; making it so is usually
> impossible).
>
> IMHO far from being niggling details, these are the crux of the reason that
> the conventional use of P values to decide what is scientifically "valid"
> and what is not is a pox upon science. This is not an original view, of
> course.
>
> Don't want to stir up a hornet's nest, so feel free to silently dismiss. But
> contrary views are welcome, as always.
>
> No more from me on this -- I promise!
>
> -- Bert
>
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-- 
Frank E Harrell Jr   Professor and Chairman        School of Medicine
                      Department of Biostatistics   Vanderbilt University