Numerous inventory models exist, and various approaches can be applied, depending on your needs and ideas:
Movement Inventory is an inventory classification for items that are held due to a process delay while some inventory is moved from one location to another.
Economic Inventory is the physical inventory plus replenishments ordered but not yet received less items sold but not yet delivered. It indicates the amount exposed to the risk of fall in prices. Also called economic stock.
Book Inventory is the amount of inventory recorded that is presently in stock.
Deterministic Inventory Control is a stock method based on the assumption that all parameters and variable associated with an inventory are known or can be computed with certainty, and that the replenishment lead time is constant and independent of the demand.
Probabilistic Inventory Model is where there are multiple possible outcomes, each having varying degrees of certainty or uncertainty of its occurrence. Probabilistic is directly related to probabilities and therefore is only indirectly associated with randomness. This method describes the mathematical analysis (and that of its consequences).
Stochastic Inventory Model is that which contains a random element, hence being unpredictable and without a stable pattern or order. All natural events are stochastic phenomenon. Businesses and open economies are stochastic systems because their internal environments are affected by random events in the external environment. The Stochastic Model conveys the idea of (actual or apparent) randomness. The term ‘stochastic’ is Greek for being skillful in aiming or guessing.