model {
  for (i in 1:n){
      for (j in 1:p){
          Y[i , j] ~ dbern ( prob[i , j])
          logit(prob[i , j]) <- beta[j] * ( theta[i] - alpha[j])
      }
      theta[i] ~ dnorm(0.0 , 1.0)
  }

  for (j in 1:p){
      alpha[j] ~ dnorm(m.alpha , pr.alpha)
      beta[j] ~ dnorm(m.beta , pr.beta) I(0 , )
  }
  pr.alpha <- pow(s.alpha , -2)
  pr.beta <- pow(s.beta , -2)
}
