Mixed Effects Model Power Calculations

Is there an R package available that would facilitate doing a power/sample
size analysis for linear mixed effects models?

I have seen the Java applets made available by Russell Length which would
seem to be able to handle most any lme, but there is little documentation
and it's not clear how the models need to be formulated.

Rick B.

On Ti, 2005-08-16, 21:17, rab45+ at pitt.edu skrev:

Is there an R package available that would facilitate doing a 
power/sample
size analysis for linear mixed effects models?

I'm not aware of such a package (others might be...).

When it comes to sample size calculations, especially for tricky 
designs
and/or advanced methodology, simulation is usually the best 
approach. An
example using `lme' can be found at

http://maven.smith.edu/~nhorton/R/


HTH,
Henric

I have seen the Java applets made available by Russell Length which 
would
seem to be able to handle most any lme, but there is little 
documentation
and it's not clear how the models need to be formulated.

Rick B.

I don't know what specific application Rick has in mind, but if there
is possibility of missing values (which is common, e.g., in
longitudinal studies) then this should also be taken into account in
the power calculations.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message -----
From: "Henric Nilsson" <henric.nilsson at statisticon.se>
To: <rab45+ at pitt.edu>
Cc: <r-help at stat.math.ethz.ch>
Sent: Wednesday, August 17, 2005 10:42 AM
Subject: Re: [R] Mixed Effects Model Power Calculations

On Ti, 2005-08-16, 21:17, rab45+ at pitt.edu skrev:

Is there an R package available that would facilitate doing a
power/sample
size analysis for linear mixed effects models?

I'm not aware of such a package (others might be...).

When it comes to sample size calculations, especially for tricky
designs
and/or advanced methodology, simulation is usually the best
approach. An
example using `lme' can be found at

http://maven.smith.edu/~nhorton/R/


HTH,
Henric

I have seen the Java applets made available by Russell Length which
would
seem to be able to handle most any lme, but there is little
documentation
and it's not clear how the models need to be formulated.

Rick B.