[R] Post hoc power analysis for mixed-effects models

[Ben Bolker]

Kota Hattori <kota.hattori <at> canterbury.ac.nz> writes:

>  Dear all, I have been searching ways to run power analysis for
> mixed-effects models. However, I have not been successful in the
> research. Today I would like to ask your help. As long as I see from
> my search, Martin Julien wrote a package called pamm for the power
> analysis. One of the limitations in the current version is that pamm
> cannot handle categorical fixed variables. Todd Jobes introduced his
> script to run power analysis for mixed-effects models
> (http://toddjobe.blogspot.co.nz/2009/09/
    power-analysis-for-mixed-effect-models.html).
> However, some parts of the script is beyond my knowledge. I am not
> sure if I can run power analysis with categorical variables
> either. Is there anybody who has run post hoc power analysis for
> mixed-effects models? If you have experiences, I would like to ask
> your help. Thank you very much for taking your time.

  I share David Winsemius's concerns about post hoc power analysis:
this thread from 2008 gives some important reading.
<http://comments.gmane.org/gmane.comp.lang.r.ecology/472>

  The script you reference is a pretty generic introduction
to simulating data corresponding to a fixed + random effects
structure, so it should certainly be adaptable to categorical
variables.  

  This doesn't immediately solve your problem, but you might
work through chapter 5 of
http://www.math.mcmaster.ca/~bolker/emdbook/book.pdf
to strengthen your background knowledge ...

  Further mixed-model-relevant questions should probably
go to r-sig-mixed-models at r-project.org.

  Ben Bolker