## 3 Results
When observing the other variables, optical ink density (_Density C_) and ink depth penetration (_Penetration C_), it cannot be concluded that they have a significant impact on the print-through (_Print-through C_), because the obtained values of Wald statistics for _Density C_ are 0.01780 with a \(p\)-value of 0.89380, while for _Penetration C_, the values of Wald statistics are 0.00080 with a \(p\)-value of 0.97701. From the above, it can be concluded that relative to the reference value, that is, the reference paper R, the type of paper (70R30W, 70R30B, and 70R30T) has a significant impact on the variable print-through (_Print-through C_), while the variables optical ink density (_Density C_) and ink depth penetration (_Penetration C_) are not statistically significant in this model. Considering the \(p\)-value for each of the three alternative papers (70R30W: \(p\) < 0.0001, 70R30B: \(p\) < 0.0001, and 70R30T: \(p\) < 0.0001), all three types of alternative papers exhibit statistically significant differences compared to the reference paper R concerning the print-through variable (_Print-through C_). However, to determine which one is closest to the reference paper, it is essential to look at the effect size, that is, the values of Wald statistics (70R30W: 46.06860, 70R30B: 42.59720, and 70R30T: 100.59890). Paper 70R30T has the highest Wald statistic, indicating the most significant difference compared to the reference paper. Papers 70R30B and 70R30W have lower Wald statistics compared to 70R30T, meaning these two types of alternative paper are statistically closer to the reference paper from recycled \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Test of All Effects**} \\  & & \multicolumn{6}{c}{**Distribution**: **NORMAL; Link Function: LOG**} \\ \cline{2-9}  & & \multicolumn{2}{c}{_Print-through C_} & \multicolumn{6}{c}{_Print-through M_} & \multicolumn{6}{c}{_Print-through Y_} \\ \hline \multirow{2}{*}{**Effect**} & **Degree of** & **Wald** & \multirow{2}{*}{_p_**-Value**} & **Degree of** & **Wald** & \multirow{2}{*}{_p_**-Value**} & **Degree of** & **Wald** & \multirow{2}{*}{_p_**-Value**} \\  & **Freedom** & **Statistics** & & & & & & & \\ \hline Intercept & 1 & 4.33690 & 0.03729 & 1 & 0.03662 & 0.84825 & 1 & 0.27780 & 0.59815 \\ R & 0 & & & & & & & 0 \\
70R30W & 1 & 46.06860 & 0.00000 & 1 & 12.36398 & 0.00044 & 1 & 80.78472 & 0.00000 \\
70R30B & 1 & 42.59720 & 0.00000 & 1 & 41.52183 & 0.00000 & 1 & 1.41681 & 0.23393 \\
70R30T & 1 & 100.59890 & 0.00000 & 1 & 39.60972 & 0.00000 & 1 & 9.81380 & 0.00173 \\ Density & 1 & 0.01780 & 0.89380 & 1 & 1.92370 & 0.16544 & 1 & 0.08607 & 0.76923 \\ Penetration & 1 & 0.00080 & 0.97701 & 1 & 1.60490 & 0.20521 & 1 & 9.56031 & 0.00199 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The results of the multiple regression analysis for samples printed with cyan, magenta, and yellow gravure inks. wood pulp. Since Wald statistics measure how much the estimated coefficient differs from zero, a higher absolute value of Wald statistics indicates a higher likelihood that the corresponding coefficient is not zero, pointing to a greater significance of the variable in the model. Hence, it can be concluded that alternative paper 70R30T has the most substantial difference compared to reference paper R, while alternative papers 70R30W and 70R30B also show significant differences, but the differences are less pronounced than in the case of paper with triticale straw pulp (70R30T) when observing the print-through on samples printed with cyan ink. By observing the obtained values of Wald statistics and \(p\)-values for magenta prints, it can be concluded that for the alternative paper 70R30W (Wald statistics = 12.36398 and \(p\) = 0.0004), there is a statistically significant influence of the paper on the print-through (_Print-through M_) compared to the reference category, that is, reference paper R. The low \(p\)-value (\(p\) = 0.00044) indicates that this difference is statistically significant.