Re: [R] post hoc statistical power

From: John Fox <>
Date: Tue, 08 Apr 2008 20:33:35 -0400

Dear Yuelin,

Another paper critical of post-hoc power calculations is Hoenig and Heisey, 2001. "The Abuse of Power: The Pervasive Fallacy of Power Calculations for Data Analysis." The American Statistician, 55, 19-24. Hoenig and Heisey show that so-called "observed power" is simply a re-expression of the p-value.

I hope this helps,

John Fox, Professor
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4

> -----Original Message-----
> From: [mailto:r-help-bounces_at_r-
>] On Behalf Of Yuelin Li
> Sent: April-08-08 12:47 PM
> To:
> Subject: [R] post hoc statistical power
> I remember reading about post hoc statistical power on R-help. But I
> can't seem to find them with RSiteSearch("post hoc statistical power")
> and variations of it.
> I would like to learn more about post hoc statistical power, its
> meaningfulness, advantages and disadvantages. I thought the issue was
> settled after Tukey's 1993 paper about post hoc statistical power
> being "essentially meaningless once the experiment has been done".
> But they seem to be used, and sometimes encouraged
> (e.g.,
> I do not intend to start a debate. I simply would like to learn
> more. Can anyone suggest a few articles? Thanks,
> Yuelin.
> Tukey JW. Tightening the clinical trial. Control Clin Trials.
> 1993;14:266-285.
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