中文摘要：

田口先生提出的质量特性损失函数是用二次项来表示的，对于望大特性而言，质量特性实际上不可能达到无穷大。讨论了不能忽略一次项损失时，望大特性质量损失函数应采用二次式表示。研究了二次式损失函数中一次项损失系数和二次项损失系数确定的方法。比较分析了二次式损失函数中一次项损失和二次项损失的大小。本文的研究结果显示，田口先生经典的二次项损失函数是二次式损失函数的一种形式。实际问题也验证了本文的研究成果。

英文摘要：

At present, quality loss function is only a quadratic term. For the larger the better charac- teristic, it＇s unadvisable. The determination of the loss coefficient of the linear term and quadratic term is discussed, and the comparative analysis of the loss of the linear term and quadratic term is conducted. The results show that the loss function of the quadratic term is only a special form of the quality loss function of the larger the better characteristic. At last, the results is verified by the practical problem.