model
   {
      for( i in 1 : N ) {
         Y[i] ~ dnorm(mu[i],tau)
         mu[i] <- alpha + beta * (x[i] - xbar)
      }
      tau ~ dgamma(0.001,0.001) sigma <- 1 / sqrt(tau)
      alpha ~ dnorm(0.0,1.0E-6)
      beta ~ dnorm(0.0,1.0E-6)   
   }