在本文中，利用非中心卡方分配的方法及Patnaik(1 949) 、Zar(1978) 、Wilson-Hilferty(1931 )所提出的近似式，以區間估計的觀念探討製程能力指標，並考慮在α 風險及檢定力的條件下，分別推導出C 指標的最小臨界值和C 指標pm的最大臨界值，以及相對的最適樣本數，以做為製程能力檢定的決策準則，且提供了最適樣本數的選取參考。 In this paper, we use the approach of the non-central chi-square distribution and some approximated formulae, proposed by Patniak(1949), Zar(1978) and Wilson-Hilferty( 1931), to derive the minimum critical values of the process index C pm and the maximum critical values of the process index C pp under some given values of the a -risk and the power. The corresponding optimal sample sizes are also determined.
