## 4 Discussion  
Based on the graphs and results provided in the previous section, it is evident that the suggested apparatus effectively captures biometric data from users during writing tasks. Despite the limited sample size of five users, the collected measurements adequately reflect the expected behavior of the data. Particular sensors, such as the magnetometer, exhibit noticeable variations when the user employs a stylus as opposed to a finger for writing. The discrepancy arises due to the varying distances between the magnets and the sensor while using either a stylus or a finger for writing. Furthermore, the orientation of the magnet contributes greatly to the variation in readings due to finger or stylus rotation. Nevertheless, the anticipated discrepancies among the readings for various users become apparent when examining the magnetometer readings for each input modality. Additionally, the similarity can be observed in multiple tries of the same user while composing identical sentences. The acceleration and gyroscope measurements from the smartwatch show valuable insights, which are comparable to the data obtained from other sensors. Similarities across \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Sensor/Measurement** & \begin{tabular}{c} **Intra-Person** \\ **Variability** \\ \end{tabular} & \
\begin{tabular}{c} **Inter-Person** \\ **Variability** \\ \end{tabular} &
\begin{tabular}{c} **Classification** \\ **Potential (CP)** \\ \end{tabular} \\ \hline Accelerometer & 8.5 & 117.23 & 13.79 \\ \hline Stylus orientation & 0.28 & 2.76 & 9.86 \\ \hline Magnetometer & 63.95 & 493.07 & 7.71 \\ \hline Stylus translation & 1.94 & 8.06 & 4.15 \\ \hline Stylus rotation & 5.42 & 18.52 & 3.42 \\ \hline Pressure & 0.34 & 0.97 & 2.85 \\ \hline Gyroscope & 198.83 & 495.22 & 2.49 \\ \hline Touch position & 103.37 & 220.4 & 2.13 \\ \hline Piezoelectric sensor 1 & 73,069.27 & 103,811.43 & 1.42 \\ \hline Piezoelectric sensor 2 & 16,213.3 & 26,570.19 & 1.64 \\ \hline Velocity & 329,110.2 & 319,536.78 & 0.97 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Comparison of classification potential (CP) for various sensors and measurements from the proposed apparatus. The data were gathered from stylus-writing tasks where five participants are wrote ’We trust you’ five times. The units are identical to those presented in the previously shown tables (omitted here for clarity), while the CP is unitless. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Sensor/Measurement** & \begin{tabular}{c} **Intra-Person** \\ **Variability** \\ \end{tabular} & \
\begin{tabular}{c} **Inter-Person** \\ **Variability** \\ \end{tabular} &
\begin{tabular}{c} **Classification** \\ **Potential (CP)** \\ \end{tabular} \\ \hline Accelerometer & 4.7 & 124.68 & 26.53 \\ \hline Magnetometer & 80.61 & 542.8 & 6.73 \\ \hline Touch size area & 0.02 & 0.09 & 4.5 \\ \hline Gyroscope & 162.89 & 405.33 & 2.49 \\ \hline Touch position & 100.89 & 226.56 & 2.25 \\ \hline Piezoelectric sensor 1 & 81,153.56 & 110,985.47 & 1.37 \\ \hline Piezoelectric sensor 2 & 13,116.84 & 24,172.57 & 1.84 \\ \hline Velocity & 1561.99 & 2093.88 & 1.34 \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Comparison of classification potential (CP) across different sensors and measurements from the proposed apparatus. The data were collected from finger-writing tasks where five participants each wrote ’We trust you’ five times. The units match those in the previously presented tables (excluded here for clarity), and CP has no units. different writing attempts by the same user are evident as well as variations in readings among users. This is noticeable from the inter-person variability for both the stylus and finger input modalities. A smartwatch equipped with more advanced sensors is likely to deliver even better results, making this a promising area for further research. Regarding the results pertaining to the measuring of the writing velocity, there are evident patterns of consistency among the same participants.