A model to estimate service levels when a portion of the master production schedule is frozen

An illustrative example is presented to show how freezing can affect performance of the master production schedule (MPS). An analytical expression is then derived for the expected customer service level when a specified number of orders in the MPS is frozen. The analytical model is used to estimate the effects of MPS freezing in a variety of situations. Controlled simulation experiments are then run to assess the usefulness of the analytical model in estimating customer service under more complex situations. The results suggest that the impact of MPS freezing on customer service is predictable and not as severe as might be anticipated.