model
      {
         for( i in 1 : N ) {
            r[i] ~ dbin(p[i],n[i])
            b[i] ~ dnorm(0.0,tau)
            logit(p[i]) <- alpha0 + alpha1 * x1[i] + alpha2 * x2[i] +
               alpha12 * x1[i] * x2[i] + b[i]
         }
         alpha0 ~ dnorm(0.0,1.0E-6)
         alpha1 ~ dnorm(0.0,1.0E-6)
         alpha2 ~ dnorm(0.0,1.0E-6)
         alpha12 ~ dnorm(0.0,1.0E-6)
         tau ~ dgamma(0.001,0.001)
         sigma <- 1 / sqrt(tau)
      }