Optimal Ordering Model for Perishable Items with Stochastic Demand Given A Limited Returns and Backup Policy

既定限量退回與備援政策下具隨機性需求之易腐性商品的最佳訂購模型

由於高競爭性之易腐性產品經常面對相當程度起伏波動的市場需求，使得零售商的獲利性往往受到不利衝擊。鑑於此一情況，供應商目前已建立多種主要基於實現通路合作與風險分擔之政策，以之做為有效工具來減輕需求不確定風險，如此將極可能有助於增進整體通路利益。其中一種政策為供應商承諾零售商許可限量退回及提供限量備援存貨，藉以激勵零售商下訂更多訂單作為回報。此一互利合作政策對於未售出單元之殘值通常所剩無多的易腐性商品而言尤其具備價值性與必要性。為了達成此一目的，本研究延伸傳統之報童模型（Newsvendor model）以併入該一具對數常態隨機性需求之易腐性商品的限量退回與備援政策。經過周詳推導之後，本研究最終發展出一有效與實用的訂購模型，可用以最佳化訂購數量與最大化零售商的預期利潤，透過數值實例，本研究實證展示所發展之最佳訂購模型的可行性與效益性。

Competitive perishable items frequently face such sizably volatile market demand that retailer profitability is frequently unfavorably impacted. Accordingly, suppliers have presently created various policies, which are primarily based on carrying out channel coordination and risk sharing, to serve as effective instruments to ease the risk of demand uncertainty and thus potentially help improve overall channel benefits. One such policy is for suppliers to make commitments to retailers to permit limited returns and provide a limited backup inventory to incentivize retailers to place more orders in return. This coordinated policy is especially valuable and necessary for perishable items because the salvage value remaining on unsold units is often trivial. To this end, this study extends a classical newsvendor model to incorporate the limited returns and backup policy for a given perishable item with lognormal stochastic demand. Following a comprehensive deduction, an effective and practical ordering model is finally developed to optimize order quantity and maximize retailer expected profits. By means of a numerical example, this study demonstrates the workability and effectiveness of the developed optimal ordering model.