model
     {
          logLbar <- mean(logL[])
	  for( i in 1 : N ) {
            logMerc[i] <- log(MERCURY[i] )
            logL[i] <- log(LENGTH[i])
   	    logMerc[i] ~ dnorm(mu[i],tau)
	    mu[i] <- alpha[S[i]+1]+ beta[S[i]+1]*(logL[i]  -logLbar)
	  }
	 for( j in 1:16) {		
            alpha[j] ~ dnorm(alpha.s,tau.alpha)
	        beta[j] ~  dnorm(beta.s,tau.beta)
		}
		tau ~ dgamma(0.001,0.001)
		sigma <- 1 / sqrt(tau)
		alpha.s ~ dnorm(0.0,1.0E-6)	   
		tau.alpha ~ dgamma(0.1,0.1)
		beta.s ~ dnorm(0.0,1.0E-6)
		tau.beta ~ dgamma(0.1,0.1)
		alphal ~ dnorm(alpha.s, tau.alpha)
		betal ~ dnorm(beta.s, tau.beta)
		mu20 <- alphal + betal*(log(20) - logLbar)
		y20 ~ dnorm(mu20, tau)
	}