PeriodicReviewModell

PeriodicReviewModell, also known as a periodic review policy, is an inventory management approach in which stock levels are checked at fixed intervals and orders are placed to raise the inventory to a predefined target level. It contrasts with continuous review models, where order triggers respond immediately to changes in inventory.

In operation, the manager selects a fixed review interval T and an order-up-to level S. At each review time, the inventory position is observed, and if it is below S an order is placed to raise it to S. The order quantity equals S minus the current position and the order arrives after a lead time L. The coverage during the next interval depends on the demand realized over the period L + T. Demand is typically stochastic, and the policy must balance ordering, holding, and potential shortage costs.

The objective is to determine optimal T and S to minimize expected total cost over a planning horizon, potentially subject to service level constraints such as a target fill rate. In practice, parameter choices are guided by the trade-off between reduced monitoring costs (advantage of periodic reviews) and potentially higher average inventory or stockouts compared with continuous review.

Advantages of the periodic review approach include simpler monitoring requirements and better suitability for operations with regular purchasing cycles or limited visibility. Disadvantages include the possibility of larger stockouts during the interval and higher average inventory if S is set conservatively.

Variants cover backorder versus lost sales, multi-echelon systems, and approximate optimization methods. The PeriodicReviewModell is widely used in retail, manufacturing, and spare-parts management where continuous surveillance is impractical.