Hello. All,

I'm struggling with how to write a multivariate normal distribution. The mean of the multivariate normal distribution is fixed as 0 for both variables. But, the variance of one variable should be fixed to 1, while other should be free to estimate (for the model identification purpose). If both variables are free to estimate, I can simply use wishart prior to estimate variance-covariance matrix of the multivariate normal distribution. But, I MUST fix one of the variances. 

What I thought as a possible solution was

rel ~ dmnorm(mu[], prec[,]) 

mu[1]<-0
mu[2]<-0

prec[,] ~ dwish(s.prec[,],2) 

s.prec[1,1]<-1
s.prec[2,2]<-1
s.prec[1,2] <-0
s.prec[2,1] <-0

prec[1,1] <-1 # to fix the variance after variance-covarince matrix was sampled from the wishart distribution.

But, because Openbugs does not care of which argument comes first, this did not work.

Please share your idea to solve this problem with me if any.

Thanks much all!

Ashley

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