{

  lambda.C ~ dgamma( 0.001, 0.001 )
  lambda.E ~ dgamma( 0.001, 0.001 )

  for ( i in 1:n.C ) {

    C[ i ] ~ dpois( lambda.C )

  }

  for ( j in 1:n.E ) {

    E[ j ] ~ dpois( lambda.E )

  }

  effect <- lambda.E - lambda.C

}