respond to:There are three inventory control models. The first one is the single period inventory model. It determines the optimal quantity of an item when the demand is not known. The product could have a limited shelf life. For example, holiday decorations from Target or Walmart, are products that for a short period of time hold a high value. After the season ends, those holiday items are not in high demand until the following year.

There is also the multi period inventory systems which are designed so that an item will be available throughout the year. The item could be ordered systematically either by quantity or time of order, meaning there's two types of multi period inventory systems. There is the fixed order quantity aka economic order quantity, where a fixed quantity is able to be ordered at once to maintain control on inventory. A minimum number could be set for an item and when inventory reaches that number, a maximum number of that product is reordered. The fixed order quantity can determine the number of units you should order taking into consideration holding$/$ordering costs and the demand rate. An example of this would be a store that sells x amount of pants that cost $x$.$ It might cost the company a couple of dollars to hold the shirt in inventory per year and a couple of dollars to place the order. Using the economic order quantity formula you can determine the order amount that will allow for low costs and demand to be met.

The fixed time period model allows for inventory to be ordered during a previously determined interval, however the order quantity can vary. Fixed time period is driven by demand. An example of this would be the company I used to work for. They would get towels, rugs, and smelling scents ordered monthly but the quantity of the items were never consistent. It was based on time period.