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Re: st: Spearman's rank correlation coefficient - power calculation

From   Richard Goldstein <>
Subject   Re: st: Spearman's rank correlation coefficient - power calculation
Date   Thu, 19 Jun 2008 05:33:25 -0400

Sounds to me as both of the following are true:

1. you did not do a sample size estimation prior to the study

2. the reviewer is now asking for a retrospective power calculation; this is very problematic -- for an intro to the problems, and some citations, see Russ Lenth's page on power:


Theo Serge wrote:

Dear Statalist,
I would be grateful if you could help me on a problem:

Having submitted an article to a Journal, the reviewers asked me for power calculation on a Spearman’s rank correlation coefficient.

This happened although I had been very careful with the interpretation of negative findings in the manuscript. Moreover, Spearman’s rank correlation coefficient was the appropriate choice for the univariate analysis performed, due to a variety of underlying factors.

To my knowledge, there is no command through which STATA can perform power calculations on Spearman’s rank correlation coefficients.

Please inform me if there is a way to overcome this difficulty. Are there any commands I am not familiar with? Would programming STATA be of value?
What would be the optimal approach to this issue? The need for power calculations in Spearman's rank correlation coefficients seems justified.

I thank you in advance.

University of Athens, Greece
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