[R-sig-ME] MCMCglmm non-informative prior

[W Robert Long]

Hi all,

I want to set a non-informative prior on a random effect. My simplest 
model has just one random effect.

The tutorial pdf shows how to use an improper flat prior, and a proper 
Cauchy prior.  I don't think the former is appropriate for me because I 
know the parameter will not take values above 1 (or rather values above 
1 are vanishingly small). I guess a U(0,1) prior distribution would be 
ideal but I don't see any way to parameterise that. Am I thinking about 
this properly ?

As for the proper Cauchy prior which seems to accept a
additional parameter that controls the scale , I don't really understand 
this - can anyone explain it ? Can this be used in my situation ?

Thanks

Robert Long
Postgraduate Student
University of Leeds / UK