, M and d.
Vague priors are used for , M and d.
In the absence of evidence to the contrary, it was felt reasonable that the knowledge
of the location of the 
and 
was insufficient to be precise when
specifying the distribution or parameters for and M. Vague normal priors were
used for these parameters, with zero mean. The prior for d was lognormal with mean
4.8 and variance 1. This prior was based upon the average grain length for the
material under investigation.