model{
    for(i in 1:m){
    Y1998[i]~dpois(mu[i])
    mu[i]<-Exp98[i]*theta[i]
    log(theta[i])<-a0+z1[i]
z1[i]~dnorm(0,tauZ)
    }
 a0~dnorm(0,tau0)
tauZ~dgamma(2,0.5)
tau0~dgamma(2,0.5)   
    }