Glossary · metric
Service Level
The probability that a customer finds what they want when they ask — a numeric target for inventory and ordering decisions.
Fill RateService Rate
Service level expresses, as a numeric rate, how well an inventory or capacity policy meets customer demand. There are two common definitions: (1) Type-1 service level (alpha): the probability of no stockout in a given period, (2) Type-2 service level (beta) or fill rate: the percentage of demand fulfilled on a unit basis. Typical targets sit between 85–99%; high service levels mean high inventory cost, low service levels mean lower customer satisfaction. Newsvendor, (s,S) policies, production scheduling, operating-room planning, and many inventory-capacity problems carry service level as a target or constraint. The right level depends on the customer segment: a critical medication may need 99.9%, fresh produce may settle around 85%.
Örnek
If an online seller targets a 95% service level, no more than 5 stockouts per 100 orders are acceptable. That rate determines the size of the safety stock — high target → more stock, low target → less stock.