## 7 Case Analysis and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline Group & **A** & **B** & **C** & **D** & **E** & **F** & **G** & **H** & **RMSE** \\ \hline \multicolumn{10}{c}{Level} \\ \hline
1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 0.051 & 0.012 \\
2 & 1 & 1 & 2 & 2 & 2 & 2 & 2 & 0.062 & 0.023 \\
3 & 1 & 1 & 3 & 3 & 3 & 3 & 3 & 0.042 & 0.029 \\  
\"Others\" in Table 6 are regarded as errors. The variance of Factors A and B is smaller than Others, so they are considered as factors without influence. In other words, the variation caused by Factors A and B is regarded as an occasional phenomenon caused by experimental error, so these variations can be regarded as errors. The variation caused by Factors A and B is pooled to errors. The table shows the analysis result of variance after the Others term and Factors A and B are pooled to the error term. When the influence of factors reaches 90% confidence level, the table shows that those factors with enough influence are C, D, E, F, G, and H. The contribution of various control factors to the detection yield is also presented in the table. The contribution of various factors is thus validated. The contribution of a control factor represents the proportion of total quality loss caused by the variation of a factor, and it can be regarded as a simple index representing the influence of the change in a factor on total quality loss. It can be considered an index for judging the importance of factors. According to the factor response table of the SN ratio, the optimum parameter combination is A1, B3, C1, D2, E2, F3, G2, and H1. Considering the influencing factors C1, D2, E2, F3, G2, and H1, the SN ratio of the original parameter combination was compared with the SN ratio of the optimum parameter combination, as shown in Table 7. \begin{table}
\begin{tabular}{c c c c c c c} \hline Factors & SS & DOE & Var. & F & Confidence & Significance & Contribution \\ \hline A & & & Pooled & & & 0.001\% \\ B & & & Pooled & & & 0.0003\% \\ C & 301.28 & 2 & 150.64 & 9.2 & 100\% & Yes & 19.28\% \\ D & 326.93 & 2 & 163.47 & 9.6 & 100\% & Yes & 21.56\% \\ E & 255.23 & 2 & 127.62 & 8.2 & 98.6\% & Yes & 17.71\% \\ F & 189.87 & 2 & 94.94 & 6.2 & 97.2\% & Yes & 13.51\% \\ G & 209.23 & 2 & 104.62 & 6.9 & 98.1\% & Yes & 15.81\% \\ H & 168.32 & 2 & 84.16 & 5.8 & 96.9\% & Yes & 11.28\% \\ Others & & & Pooled & & & 0.002\% \\ Error & 65.31 & 5 & 13.06 & & S = 3.78 & 0.85\% \\ Total & 1516.17 & 17 & & & At least 90\% confidence & \\ \hline \end{tabular}
\end{table} 
Table 6: SN error pooling. \begin{table}
\begin{tabular}{c c c c} \hline Factors & SS & DOF & Var. \\ \hline A & 1.62 & 1 & 1.62 \\ B & 0.48 & 2 & 0.24 \\ C & 301.28 & 2 & 150.64 \\ D & 326.93 & 2 & 163.465 \\ E & 255.23 & 2 & 127.615 \\ F & 189.87 & 2 & 94.935 \\ G & 209.23 & 2 & 104.615 \\ H & 168.32 & 2 & 84.16 \\ Others & 63.21 & 2 & 31.605 \\ Total & 1516.17 & 17 & - \\ \hline \end{tabular}
\end{table} 
Table 5: Preliminary analysis of variance. \[CL=\sqrt{\frac{S^{2}}{m_{e}}+\frac{S^{2}}{m_{r}}}TINV(1\quad\alpha\%,1,dof) \tag{18}\]  
\[CL=\sqrt{4.28^{2}+4.16^{2}}=4.29.\]  
In this reproducibility experiment, the difference between prediction value and confirmation experiment value is 4.28 dB, and the 90% allowable error value is 4.29 dB. The difference value is within the permissible range, so this experiment is reliable. The optimum parameter combination is A1, B3, C1, D2, E2, F3, G2, and H1, and \(C_{pk}\) is 2.12. Considering the influencing factors C1, D2, E2, F3, G2, and H1, \(C_{pk}\) is 2.09.