An EPQ model of deteriorating substitute items under trade credit policy

This study presents a multi item EPQ model of deteriorating items under trade credit policy where items are substitute in nature. Sometimes demand for one good also depends on the stock of other related goods. The standard economic textbooks indicate that related products' for a product include complement as well as substitute products. Two goods are substitutes if one can be used in place of the other one. Many products that are on the market today have substitutes. For example, bread and crackers, stocks and bonds, two different brands of soft drinks or water etc. The change in a substitute product's stock level could alter quantity demanded for another good. Here whole profit is calculated with retailer's point of view. In this model we take different types of budget. GRG method and LINGO (13.0) is used to find the optimal solutions. Some sensitivity analyses are made and presented graphically.