From Table 5, the values of 40.16, 17.39, 43.72, 9.34 and 13.16 were the
respective estimated F-value of the independent variables
X1, X2, X3,
X4, and X5. This revealed that the
influence of most independent variable on the dependent variable was
significantly high. The F-values of all the quadratic terms of the model
are also very high. Removing the insignificant terms from the model
Equation (1), the final model equation was obtained as follows:
\begin{equation}
Y_{\ Al2O3}\ =\ 79.56\ +\ 3.39X_{1}\ +2.23X_{2}\ +\ 3.54X_{3}\ +\ 1.64X_{4}\ -1.94X_{5}\ \ 2.05X_{4}X_{5}\ \ 3.01X_{1}^{2}\ \ 3.72X_{2}^{2}\ -3.67X_{3}^{2}-\ \ 4.22X_{4}^{2}-3.41X_{5}^{2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (2)\nonumber \\
\end{equation}Table 6: Summary of regression values