# Dempster-Shafer Fusion Based on a Deep Boltzmann Machine for Blood Pressure Estimation
## 5 Discussion and Conclusions  
Under the experimental conditions, we first evaluated the accuracy between the new DBM-based DS fusion and the SBP and DBP target categories obtained from the auscultatory method, as represented in Figure 5 and Table 2. From the results, the DBM-based DS fusion scheme outperformed the SVM, SVMDS, DBN, DBNDS, and DBM single estimator. This implied that the proposed scheme represented 6% in the SBP and 4% in the DBP improvement effect compared to the DBM single estimator. Furthermore, it demonstrated 8% in the SBP and 7% in the DBP improvement effect compared with the SVM technique [28]. In addition, we confirmed that the proposed DBMDS fusion scheme provided more reliable results than the DBM single technique, as shown in Figure 5. This result showed that the estimated uncertainty was effectively reduced, as demonstrated by the solid lines in Figure 5. The ME results for the SBP and DBP computed using the DBM-based DS fusion algorithm were compared with those when using the MAA, SVM [28], SVMDS, DBN, DBNDS, and single DBM technique, as shown in Table 3. The SDEs calculated by the DBM-based DS fusion technique were acquired to be 5.34 and 4.36 mmHg for the SBP and DBP. The SDEs of the new fusion technique were improved by 3.97 and 3.04 mmHg for the SBP and DBP contrasted to those of the MAA, as represented in Table 3. These results expressed that the new fusion technique was superior to that of the single DBM technique with respect to the BP measurement uncertainty. Moreover, we performed an analysis using Bland-Altman plots to evaluate the achievement of the new fusion technique to the stethoscope measurements, as shown in Figure 6. The results in the figure indicate that the estimated BP values obtained by the DBM-based DS fusion technology closely matches the reference SBP and DBP. The range of agreement we use (bold horizontal lines in Figure 6) is for two plots (ME \(\pm\) 2 \(\times\) SDE) and most of the data is in the range (ME \(\pm\) 2 \(\times\) SDE). Thus, the achievement imply that the new fusion technique offer precise SBP and DBP contrasted to the single DBM technique. On the basis of above results, the new fusion scheme provided grades of A and A for the SBP and DBP. The achievements of the DBMDS fusion technique were 66.12% (\(\leq\)5 mmHg), 92.47% (\(\leq\)10 mmHg), and 98.82% (\(\leq\)15 mmHg) for the SBP in the given test scenario, and 77.20% (\(\leq\)5 mmHg), 97.19% (\(\leq\)10 mmHg), and 99.81% (\(\leq\)15 mmHg) for the DBP in the test scenario, as represented in Table 4. Therefore, we proved that the probabilities of the BHS criteria were superior to those of the other techniques that obtained grades for the SBP and DBP, as shown in Table 4.  
In conclusion, the proposed DBMDS fusion scheme acquired lower SDEs of MEs for the SBP and DBP contrasted with the DBM single estimator. This work thus provides an accurate BP category and offers a solution that can reduce the estimation uncertainty. Although the accuracy and stability are enhanced owing to the proposed DBMDS fusion scheme, our future study will try how the proposed fusion method behaves on individual algorithms.