## 4 Discussion  
According to the ANOVA results, the samples with 4R and 6R were included in the third and second homogeneous subset for the front visibility, respectively. The control comfort for these two samples in use patterns (b) and (c) was included in the second homogeneous subset. In addition, the grip comfort for the sample with 10R in usage pattern (d) belonged to the second homogeneous subset. The sample with 8R was included in the first homogeneous subset for all analyses, while other samples were included in second or third homogeneous subset. There were some cases where other samples were evaluated better than the sample with 8R, however, there were no statistically significant \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Source** & \multicolumn{3}{c}{**Sum of Squares**} & \multirow{2}{*}{**df**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{\(F\)} & \multirow{2}{*}{\(p\)} \\  & & & **Type** & & **Square** & & \\ \hline \multirow{6}{*}{Sample} & \multirow{3}{*}{4R} & Between & 1.119 & 3 & 0.373 & 0.200 & 0.896 \\  & & Within & 290.475 & 156 & 1.862 & & \\  & & Total & 291.594 & 159 & & & \\  & & Between & 1.250 & 3 & 0.417 & 0.270 & 0.847 \\  & & Within & 240.750 & 156 & 1.543 & & \\  & & Total & 242.000 & 159 & & & \\  & & Between & 4.025 & 3 & 1.342 & 0.911 & 0.437 \\  & & Within & 229.750 & 156 & 1.473 & & \\  & & Total & 233.775 & 159 & & & \\  & & Between & 23.919 & 3 & 7.973 & 5.034 & 0.002 \\  & & Within & 247.075 & 156 & 1.584 & & \\  & & Total & 270.994 & 159 & & & \\ \hline \multirow{6}{*}{Pattern} & \multirow{3}{*}{(a)} & Between & 5.950 & 3 & 1.983 & 1.226 & 0.302 \\  & & Within & 252.450 & 156 & 1.618 & & \\  & & Total & 258.400 & 159 & & & \\  & & Between & 4.100 & 3 & 1.367 & 0.953 & 0.417 \\  & & Within & 223.800 & 156 & 1.435 & & \\  & & Total & 227.900 & 159 & & & \\  & & Between & 6.519 & 3 & 2.173 & 1.519 & 0.212 \\  & & Within & 223.175 & 156 & 1.431 & & \\  & & Total & 229.694 & 159 & & & \\  & & Between & 4.819 & 3 & 1.606 & 0.812 & 0.489 \\  & & Within & 308.625 & 156 & 1.978 & & \\  & & Total & 313.444 & 159 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Results of three-way mixed ANOVA for front/side visibility (Test result of within subject effects). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Evaluation** & \multirow{2}{*}{**Source**} & \multirow{2}{*}{**Sum of Squares**} & \multirow{2}{*}{**df**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{\(F\)} & \multirow{2}{*}{\(p\)} & \multirow{2}{*}{\(\eta_{p}^{2}\)} \\
**Factor** & & & **Type III** & & **Square** & & \\ \hline Front & Sample & 163.419 & 3 & 54.473 & 62.281 & 0.000 & 0.615 \\ Visibility & Error (Sample) & 102.331 & 117 & 0.875 & & & \\ Side & Sample & 6.650 & 3 & 2.217 & 1.772 & 0.156 & 0.043 \\ Visibility & Error (Sample) & 146.350 & 117 & 1.251 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Results of one-way ANOVA for stability by each sample and usage pattern. differences in those cases. Thus, it could be concluded that 8R is the optimal radius for the curvature of the edge screen in a smartphone. In the case of grip comfort, only a sample with 10R showed a statistically significant effect of the usage pattern on grip comfort. As a result of the post hoc analysis, it was confirmed that usage patterns (a), (d) and (c) had significant differences in 10R. In particular, the value of grip comfort in usage pattern (d) was found to be the lowest. Grip comfort is the one of the most common patterns for people using smartphones. Through this study, when the side curvature was 10R, it was confirmed that the value grip comfort for the usage pattern related to holding the smartphone was the lowest. Therefore, it can be seen that designing the side curvature as 10R should be avoided. In the case of control comfort, it was confirmed that there was a statistically significant difference in samples and interaction effect between the sample and usage pattern.