Define and briefly discuss the ABC, EOQ, materials requirements planning (derived demand), and just-in-time inventory management systems. When is each appropriate?

Very briefly, under ABC, you segregate inventory into three groups based on their percent of inventory value and percent of inventory items. The EOQ allows you to determine the optimal order amount by assuming inventory depletes at a constant rate, among other things. The EOQ model can be modified to incorporate safety stocks and reorder points. Under MRP, finished goods inventories are set, then you work backwards to determine the optimal levels of work in process and raw materials inventories. With JIT, the goal is to minimize inventory and maximize turnover, keeping just enough inventory on hand to meet production or sales needs. This type of inventory management requires stable and dependable suppliers.