## 4 Experimental Results
### Statistical Results  
This study used the ANN, MLR, SVM, LSTM, and GP algorithms [17; 31] as conventional algorithms to evaluate the performance of the proposed GFSDP algorithm. The first experiment obtained the objective MAE and SDE results. The MAEs of the SBP (12.23 mmHg) and DBP (8.33 mmHg) obtained using the ANN algorithm were compared with the reference BP shown in Table 7. The MAEs of the MLR algorithm for the SBP (12.49 mmHg) and DBP (7.67 mmHg) were compared with the reference BP. Table 7 shows the MAEs of the SBP (11.37 mmHg) and DBP (7.23 mmHg) obtained using the SVM algorithm. The MAEs of LSTM algorithm for the SBP (10.78 mmHg) and DBP (6.98 mmHg) were compared with the reference BP. Finally, the MAEs of the SBP (10.03 mmHg) and DBP (6.70 mmHg) acquired using the GP algorithm are shown. As shown in Table 7, the proposed GFSDP algorithm obtained lower MAEs for the SBP (7.66 mmHg) and DBP (5.47 mmHg) compared with the conventional ANN, MLR, SVM, LSTM, and GP algorithms. The GFSDP algorithm was compared with the conventional ANN, MLR, SVM, LSTM, and GP algorithms, according to the British hypertension protocol (BHS) [46]. The MAEs for the three groups of less than 5 mmHg, less than 10 mmHg, and 15 mmHg were evaluated. Table 8 shows the BHS grading obtained using the GFSDP algorithm: grades C and B were obtained for the SBP and DBP, respectively. The readings obtained using the proposed method in the test scenario were 49.49% (\(\leq\)5 mmHg), 73.01% (\(\leq\)10 mmHg), and 84.97% (\(\leq\)15 mmHg) for the SBP and 60.26 (\(\leq\)5 mmHg), 85.39 (\(\leq\)10 mmHg), and 93.74 (\(\leq\)15 mmHg) for the DBP. The probabilities of the proposed algorithm based on the BHS were higher than those obtained using the conventional ANN, MLR, SVM, LSTM, and GP algorithms, as shown in Table 8.  
Table 9 shows the SDEs of the MEs for the SBP (15.68 mmHg) and DBP (12.75 mmHg) obtained using the ANN algorithm compared with the reference BP. In addition, the SDEs of the MEs for the SBP (15.93 mmHg) and DBP (11.21 mmHg) from the MLR algorithm, for the SBP (14.70 mmHg) and DBP (10.96 mmHg) obtained using the SVM algorithm, and for the SBP (14.22 mmHg) and DBP (9.87 mmHg) from the LSTM algorithms are also presented. Table 9 shows the SDEs of the MEs for the SBP (13.30 mmHg) and DBP (9.28 mmHg) obtained using the GP algorithm. The GFSDP algorithm obtained lower SDEs of the MEs for the SBP (10.83 mmHg) and DBP (8.31 mmHg) than the conventional ANN, MLR, SVM, and GP algorithms. In addition, the Bland-Altman method [48] comparing the proposed GFSDP algorithm with the reference ABP is shown in Figure 5. The agreement between the conventional SVM and ABP reference values was also compared by Bland-Altman \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**SBP (SDE)**} & \multicolumn{3}{c}{**DBP (SDE)**} \\
**Methods** & **95\% CI** & **Lower Cls** & **Upper Cls** & **95\% CI** & **Lower Cls** & **Upper Cls** \\ \hline ANN\({}_{\text{NT}}\) & 15.81 (10.23) & 114.39 (11.35) & 130.21 (11.82) & 10.96 (6.73) & 65.88 (4.05) & 76.76 (5.12) \\ MLR\({}_{\text{GT}}\) & 18.54 (10.30) & 113.37 (10.66) & 131.91 (10.99) & 7.31 (4.80) & 66.08 (1.51) & 73.38 (3.60) \\ SVM\({}_{\text{GT}}\) & 20.83 (9.83) & 112.16 (8.55) & 132.99 (10.36) & 6.05 (3.54) & 66.26 (2.80) & 72.32 (2.84) \\ LSTM\({}_{\text{ST}}\) & 18.61 (10.13) & 113.20 (9.68) & 131.81 (9.83) & 6.48 (4.10) & 65.88 (3.25) & 72.36 (3.40) \\ GP & 21.38 (3.56) & 120.92 (10.43) & 142.30 (8.03) & 13.74 (1.19) & 64.83 (2.88) & 78.57 (3.17) \\ GFSDP & 20.09 (3.27) & 123.49 (15.59) & 143.58 (13.08) & 13.98 (1.33) & 64.42 (1.97) & 78.40 (2.25) \\ GFSDP\({}_{\text{BT}}\) & 11.19 (8.59) & 118.34 (7.77) & 129.53 (10.07) & 2.19 (2.47) & 70.75 (1.34) & 75.94 (2.28) \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Summary of the CIs for SBP and DBP compared to the proposed and conventional methods, where ST denotes the Student’s t-distribution and BT is the bootstrap method.