[R-sig-ME] [Q] MCMCglmm priors

[GMail (KU)]

Dear R users,

While I was trying to learn MCMCglmm by following MCMCglmmCourseNotes.pdf, I ran into a few questions, and am looking for some help.

First, for some reason, I cannot load the "Traffic" data set. When I did "data(Traffic)", I got the following warning message:
Warning message:
In data(Traffic) : data set 'Traffic' not found

Since I failed to load the Traffic data set, I was not able to following the examples in the MCMCglmmCourseNotes.pdf. (By the way, I am using the latest version of R (R version 2.12.0) on Mac OS X Snow Leopard (v. 10.6.5). Can any one help me solve this problem?

Second, I understand that MCMCglmm uses Inverse-Wishart distribution to specify a prior for variances. But, unfortunately, I am not used to Inverse-Wishart distribution. Could someone explain how the inverse-Wishart distribution is related to other distributions, such as uniform, normal distributions, that were often used in WinBUGS/JAGS? I know how to specify priors using uniform and normal distributions in WinBUGS/JAGS, but could not figure out how to use the inverse-Wishart distribution. 

Any comments would be highly appreciated!

Young-Jin Lee