Hello,

A simplified representation of my model is:

multinomial[**y**|N,**P**]dirichlet[**P**|**alpha**]dirichlet[**alpha**/sum(alphas)|**Pi** x sum(alphas)] [**Pi**|f(theta),sigma][theta] where f is the transition matrix that defines my process model.

My problem is that I need to compute "**alpha**/sum(alphas)", but I cannot because it cannot be on the LHS twice in JAGS. I tried to compute this in the data block, but I could not because alphas depend on the process model as well as the data and because of this I don't think really want to define them as data anyway. I am using the Dirichlet to be able to include the standard deviations on the estimates of the alphas.

What are your suggestions for this moment matching problem?