近幾年來高科技產業的生產技術進步快速，使得許多產品都可維持在高良率的水準，但也因其投入的技術繁多，產品製造過程的複雜度與生產所需的時間也相對提高。對於這種高成本，高良率與生產費時的產業，統計製程管制的使用更形重要，但在成本及其它多種因素的考量下，往往每次只能獲得單一觀測值的樣本，而一製程可能需要同時監控多個具有相關性的品質特性，但在樣本數為1的情況下，對製程的變異性做監控，文獻上並沒有多少有效的方法被提出來。本文針對這種情形建構出兩個新的管制圖，其主要是利用指數加權移動平均(exponentially weighted moving average)的方法得到製程共變異數矩陣的一個合理估計量，並利用這個共變異數矩陣估計量的跡數(trace)做為製程變異性的管制統計量，經由實際例子與統計模擬結果證實本文所提出的管制圖對多變量製程變異性的大多數改變有不錯的偵側效率。

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