[R-sig-ME] Logit mixed model power analysis

David Duffy David.Duffy at qimrberghofer.edu.au
Wed Sep 16 03:29:03 CEST 2015

On Wed, 16 Sep 2015, Paul Johnson wrote:

> I second what Thierry said about the pointlessness of post-hoc power 
> analysis when using the observed effect size.
>> Post-hoc power tests are not very informative. You will get a high
>> power when the signal is significant and low power when not
>> significant.

A few people defend it as an estimate of the reproducibility 
probability. Gelman and Carlin suggest plugging in a "sensible" 
(Bayesian) estimate of the true effect based on your prior knowledge, so 
you can estimate the probability of a "Type S" (sign of true effect 
could actually be opposite to your study point estimate) or "Type M" 

Cheers, David.

| David Duffy (MBBS PhD)
| email: David.Duffy at qimrberghofer.edu.au  ph: INT+61+7+3362-0217 fax: -0101
| Genetic Epidemiology, QIMR Berghofer Institute of Medical Research
| 300 Herston Rd, Brisbane, Queensland 4006, Australia  GPG 4D0B994A

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