Before revision:  We formulate a bi-level optimization problem to decide not only which of M outer scenarios to simulate and how many times to replicate at each, but also how to pool these replications such that the total simulation effort is minimized while achieving the same estimation error as the standard nested simulation  .
After revision:  We formulate a bi-level optimization problem to decide not only which of M outer scenarios to simulate and how many times to replicate at each, but also how to pool these replications such that the total simulation effort is minimized while achieving the same estimation error as the standard nested simulation precision .