## 3 Results
These results demonstrate that while individual velocity measurements are relatively stable, there is considerable variability between different individuals. Figure 13: The minimum (blue), average (red), and maximum (green) readings of the X-direction velocity between 4 users during five trials of writing the same phrase (_”We trust you”_). For the purpose of writing on the tablet, a stylus was used. The shown data are the mean values obtained from the 5 experiments per user. Since the stylus S Pen Remote SDK was incapable of reading pressure-level data, the MotionEvent object was utilized to report the pressure readings instead. In general, the pressure falls into the range of 0 (no pressure at all) to 1 (normal pressure). However, depending on the calibration of the input device, it is possible for values that are greater than 1 to be registered. Figure 15 illustrates the variations in the normalized mean pressure levels across five distinct users who each wrote the identical phrase five times. Nevertheless, it is important to note that the specified MotionEvent does not provide the ability to obtain data regarding the pressure that has been exerted when writing with a finger. For pressure metrics, the stylus data from Table 11 reveal a clear distinction between intra-person (0.367) and inter-person (0.970) distances, indicating that pressure can effectively differentiate between users, although the overall values are smaller compared to other metrics. This suggests that pressure might be a more subtle yet useful metric for user identification. Pressure data for finger input are missing due to hardware limitations that prevented the collection of pressure levels during finger input. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline  & & \multicolumn{3}{c}{**Stylus**} & \multicolumn{2}{c}{**Finger**} \\ \hline
**Measurement** & **Axis** & **Intra-Person** & **Inter-Person** & **Intra-Person** & **Inter-Person** \\ \hline \multirow{3}{*}{Velocity [pixels/s]} & X & 19,465.04 & 19,883.20 & 1112.40 & 1419.23 \\ \cline{2-6}  & Y & 328,021.36 & 325,161.88 & 1958.50 & 2786.84 \\ \cline{2-6}  & Magnitude & 329,110.20 & 319,536.78 & 1561.99 & 2093.88 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Intra-person and inter-person variability in velocity measurements during writing with both stylus and finger inputs, across the X-axis, Y-axis, and magnitude. Figure 14: The Y-direction velocity measurements for five trials of writing the same phrase (_“We trust you”_) by four users are depicted as minimum (blue), average (red), and maximum (green) values. The mean values are displayed for stylus writing obtained from five trials: one for each user. While it is not feasible to obtain data on the exact pressure level applied to the screen when using a finger, the MotionEvent object offers an estimate of the region that is pressed on the screen. When a touch is detected, the value in pixels corresponding to the touch area is adjusted with the device's range of values. Figure 16 shows the average results of five attempts by four users, in which we determine the finger-pressed area of the screen. Evidently, the mean value of the estimated screen area being touched varies among distinct users irrespective of them writing the identical phrase. Some users show a wider range of touch sizes, indicating larger fluctuations in their finger pressure or contact area. There appears to be an adaptation process where touch sizes stabilize or decrease over time. This implies that users may initially apply more pressure but adjust to a lighter touch as they continue the task. For touch size metrics, as shown in Table 12, the finger input shows a noticeable but small difference between intra-person (0.02) and inter-person (0.09) distances. This highlights a noticeable yet relatively small variation in touch size among individuals, indicating that while touch size can help distinguish users, it is a less revealing factor compared to other metrics.