## 3 Results

Table 8: Variability in orientation measurements using a stylus shows lower intra-person variability compared to inter-person variability. Data for finger writing were not available. For the magnetometer data, the results from Table 9 highlight notable differences between intra-person and inter-person variability. For magnitude measurements, the intra-person distance with the stylus is 63.95, while the inter-person distance is considerably higher at 493.07. Similarly, for the finger, the intra-person distance is 80.61 compared to a much greater inter-person distance of 542.80. This pattern of lower intra-person variability compared to much higher inter-person variability is consistent across the X, Y, and Z axes. Figure 11: Magnetometer data collected from 3 users throughout 5 trials of writing the same phrase _”We trust you”_. The minimum, average, and maximum magnetometer reading values of the sensor are represented by the green, blue, and orange lines, respectively. The values shown are the average of all 5 trials per user. Figure 12: The averaged and normalized measurements of the magnetic field in all three dimensions while writing the same phrase _”We trust you”_ five times using both a stylus and finger. The stylus outcomes are indicated by the blue line, while the orange line represents the finger readings. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline  & & \multicolumn{3}{c}{**Stylus**} & \multicolumn{2}{c}{**Finger**} \\ \hline \multirow{2}{*}{**Measurement**} & \multirow{2}{*}{**Axis**} & \multirow{2}{*}{**Intra-Person**} & \multirow{2}{*}{**Inter-Person**} & \multirow{2}{*}{**Intra-Person**} & \multirow{2}{*}{**Inter-Person**} \\ \cline{3-3} \cline{5-6}  & & X & 70.98 & & 143.40 & 63.84 & 290.57 \\ \cline{3-6} \multirow{2}{*}{Magnetometer [\(\mu\)T]} & Y & 83.23 & 540.27 & 104.12 & 625.94 \\ \cline{2-6}  & Z & 78.78 & 441.09 & 96.61 & 604.51 \\ \cline{2-6}  & Magnitude & 63.95 & 493.07 & 80.61 & 542.80 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Comparison of intra-person and inter-person variability in magnetometer measurements across the X, Y, and Z axes, and their magnitudes, for stylus and finger inputs. The velocity of touch events is monitored via the VelocityTracker Android API. It facilitates the measurement of the velocity at which a pointer, such as a finger or stylus, traverses the screen. When determining the direction and speed of gestures, it is feasible to obtain the velocity of movement independently along the horizontal (X) and vertical (Y) axes, as seen in Figures 13 and 14. In contrast to the magnetometer, the averaged minimum and maximum values for a particular user exhibit a marginally greater deviation from the mean reading values. However, the average velocity lines (red) are relatively stable within each user across trials, indicating a consistent writing speed for each individual. Moreover, noticeable variations in velocity are observed along both the X and Y axes between four distinct users. Some users exhibit a broader range of velocities (indicating larger speed fluctuations), while others have a more narrow range (indicating steadier speed). The occurrence can be anticipated, since multiple individuals will write the same sentence at varying velocities, while the pace of writing will be consistent for each user. Table 10 highlights that writing velocity measurements exhibit lower intra-person variability compared to inter-person variability for both stylus and finger inputs. For the stylus, the intra-person variability for the X-axis is 19,465.04 compared to 19,883.20 for inter-person variability, and for the Y-axis, it is 328,021.36 vs. 325,161.88. For the finger, the intra-person variability is also lower across all measurements with the X-axis showing 1112.40 compared to 1419.23 for inter-person variability and the Y-axis showing 1958.50 versus 2786.84. The magnitude data show comparable differences between intra-person and inter-person variability, which are similar to the X and Y-axis measurements.