Estimation of the Six Sigma Quality Index

The measurement of the process capability is a key part quantitative quality control, and indices are statistical measures capability. Six Sigma level represents maximum achievable capability, many enterprises have implemented improvement strategies. In recent years, studies investigated indices, including Qpk. However, Qpk contains two unknown parameters, namely δ γ, which difficult to use in control. Therefore, whether reaches k sigma must be statistically inferred. Moreover, method sampling distribution challenging for upper confidence limits We address these difficulties present study propose methodology solve them. Boole’s inequality, Demorgan’s theorem, linear programming were integrated derive intervals Qpk, then used perform hypothesis testing. This involved case semiconductor assembly order verify feasibility proposed method.