# Understanding Balance Control in the Context of Riding a Personal Mobility Device
## 3 Results  
### Weight-Shifting Task  
#### 3.1.1 Time Measures  
The ANOVA results showed that the target distance (MT: F(1.47, 27.84) = 47.83, \(p\) < 0.001, np2 = 0.72; MT\({}_{\text{PMS}}\): F(2, 38) = 39.32, \(p\) < 0.001, np2 = 0.67), target direction (MT\({}_{\text{PMS}}\): F(4, 76) = 5.70, \(p\) < 0.001, np2 = 0.23), and interaction of the target distance and direction (MT\({}_{\text{PMS}}\): F(8, 152) = 2.65, \(p\) = 0.009, np2 = 0.12) had significant effects on the time measures. In Table 2, superscripts of the uppercase and lowercase are used to denote the significant difference within one factor the distance or the direction respectively. In the post-hoc tests (Table 2), the MT and MT\({}_{\text{PMS}}\) significantly increased with increasing target distance. The MT\({}_{\text{PMS}}\) values were relatively larger in the E and W directions than in the other directions. Regarding the interaction effects on the MT\({}_{\text{PMS}}\), all simple effects in each level of distance and direction showed significant differences (Table 3). In Table 3, superscripts of the uppercase and lowercase are used to denote the significant difference within one factor by the other. The uppercase letters indicate a significant difference between the target distances in the same column. The lowercase letters indicate a significant difference between the target direction in the same row. As an example, the MT\({}_{\text{PSM}}\) showed a significant difference between Distance 3 (1.74\({}^{\text{B}}\)) and others (1.28\({}^{\text{A}}\) and 1.10\({}^{\text{A}}\)). It also showed significant differences between the direction NE (1.44\({}^{\text{A}}\)), N (1.16\({}^{\text{B}}\)), and W (0.99\({}^{\text{C}}\)). The post-hoc tests showed that the MT\({}_{\text{PMS}}\) values in the N direction significantly increased when the target distance increased. In the E and NE directions, the MT\({}_{\text{PMS}}\) values were significantly small at distance 1 and distance 2 compared to those at distance 3. There were no significant differences between the values at distance 1 and distance 2. However, the MT\({}_{\text{PMS}}\) values were significantly large at distance 2 and distance 3 compared to those at distance 1, but there were no significant differences between the values at distance 2 and distance 3 in the W and NW directions. \begin{table}
\begin{tabular}{c c c} \hline
**Type of Task** & **Classification** & **Outcome Measures** \\ \hline \multirow{4}{*}{Weight-shifting} & Time & MT, MT\({}_{\text{PSM}}\) \\  & Fluency & TE\({}_{\text{PSM}}\), MD, DC, d\({}_{\text{NMP}}\) \\  & Accuracy & TES\({}_{\text{SM}}\), DT, ME, TA \\  & Subjective assessments & PP, ET, PS, PC \\ \multirow{4}{*}{Maintaining balance} & Time-domain measures & MDIST, MDIST\({}_{\text{AP}}\), MDIST\({}_{\text{ML}}\), RDIST\({}_{\text{AP}}\), RDIST\({}_{\text{ML}}\), MVEL, \\  & & MVEL\({}_{\text{AP}}\), MVEL\({}_{\text{ML}}\), AREA\({}_{\text{CC}}\), AREA\({}_{\text{CE}}\) \\ \multirow{4}{*}{Maintaining balance} & Objective assessments & PP, ET, PS, PC \\ \hline \end{tabular}
\end{table} 
Table 1: Outcome measures derived from the COP data and subjective assessments in the weight-shifting and balance tasks. post-hoc tests revealed that a farther target distance increased the (a) total length of the PSM movement, (b) maximal deviation along the off-axis, and (c) NMP distance (Table 2). In the post-hoc results of the target direction, the PSMs in the diagonal directions (NE and NW) showed relatively longer and larger trajectories with low directional control. In contrast, those in the E and W directions were similar but show different COP movements with shorter trajectories, better directional control, and longer NMP distance (Table 2). Regarding the interaction effects on the MD and d\({}_{\text{NMP}}\), all simple effects in each level of distance and direction showed significant differences (Table 3).