假設供應商與顧客之品質鏈使用評等系統。在此系統中一個供應商如果在一段時間內，有不良品給顧客，則該供應商會被降等，如果在該段時間內，沒有不良品給顧客，則該供應商會被升級。本論文利用隨機過程模式，假設馬可夫性質，利用反覆演算法，計算評等系統供應商之最適品質策略，該策略決定供應商何時該自行報銷不良品或宣告給顧客，以達到最適品質成本。

Assume a supplier/customer management chain has a quality rating system. In this system, a supplier who did not make any nonconforming lot to his customer during one period are entitled to a discount membership. If he declared one or more nonconforming lots to the customer, then he is penalized by an increase of membership. This paper describes how to compute the optimal strategy for quality rating system. The strategy determines the supplier whether or not to declare a nonconforming lot to his customer. The model contains stochastic process, Markovian property, and iterative algorithm.