The undershoot of the reorder point: Tests of an approximation

We investigate a widely used approximation for the mean and variance of the undershoot. The approximation is based on the limit of the excess random variable of a renewal process as the order size approaches infinity. In the current business environment which emphasizes small batch sizes and frequent deliveries, many inventory systems order in batch sizes that are not large. We investigate the potential error that could be introduced by using the approximation for a variety of batch sizes and demand distributions.