I had faced difficulties in calculating sample size for a cluster randomized controlled trail with three groups (one control and two different intervention groups)?Do you have some advice or recommendation?Is there assumption what rho (ICC), coefficient of variation, cluster number and cluster size should be? Which statistical software is appropriate for calculating sample size for a cluster randomized controlled trail?
This will give you valuable input
https://www.ncbi.nlm.nih.gov/pubmed/23017638
For general orientation on this - see
http://www.bristol.ac.uk/cmm/software/mlwin/mlwin-resources.html#datadesign
This software will allow you to work out the 'cost' of different designs and will allow you to see the gains (which can be very important) from taking into account a pre-intervention measure; it is easy to use
Optimal Design for Longitudinal and Multilevel Research Documentation for the “Optimal Design” Software
http://www.stat.cmu.edu/~brian/463/week14/od/od-manual-20111016-v300.pdfhttp://sitemaker.umich.edu/group-based/optimal_design_software
For a more bespoke approach this software enables a 'sandpit' approach so you can mimic your actual problem as closely as possible
http://www.bristol.ac.uk/cmm/software/mlpowsim/
the manual is a very good primer on the underlying concepts.
And as a UK academic you can get a free copy of MLwiN to undertake the analysis http://www.bristol.ac.uk/cmm/software/mlwin/download/
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