本文在一家共同製造商與兩家零售商的通路架構下，探討零售商市場競爭策略的選擇。結果發現，在線性需求函數設定下，零售商將會採取數量競爭的方式，但此一競爭策略不利於製造商。同時，得出製造商會提出數量折扣(quantity discounts)的誘因，零售商之間的競爭會由數量競爭轉變成價格競爭。本文因此提出了製造商給予零售商數量折扣的理論基礎。

In the model of one manufacturer and two retailers, this paper investigated how retailers determine thier market competition strategies. This finding that disclosed that theses two retailers will adopt quantity competition. However, this competition is unfavorable to the manufacturer. This paper also pointed that the manufacturer will offer quantity discount as the motivation to interfere in the competiton between retailers. The quantity competition will then turn into price competition which explains why the manufacturer provides quantity discount to his retailers.