TABLE I.

Root-Mean-Squared-Errors (RMSEs) of the Intervention-Induced Blood Pressure (BP) Changes Predicted By The Models Against Reference Cuff BP Measurements

Models	RMSE (lower and upper 95% CIs) (Mean (μ) ± SD (σ))
	SP (Systolic BP)	DP (Diastolic BP)
Baseline BP Reference SPi = SP1 DPi = DP1	10.9 (9.5 – 12.4) (3.7 ± 10.2)	6.5 (5.6 – 7.3) (0.9 ± 6.4)
Demographic Reference	10.8 (9.2 – 12.7) (0.5 ± 10.8)	6.6 (5.7 – 7.5) (0.0 ± 6.6)
Finger PAT Reference ${\text{SP}}^{\text{i}}=73.2{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+{\text{SP}}^1$	10.1 (8.6 – 11.8) (2.8 ± 9.7)	6.3 (5.5 – 7.1) (0.6 ± 6.3)
Ear PAT Reference ${\text{SP}}^{\text{i}}=31.2{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+{\text{SP}}^1$	10.2 (8.6 – 11.9) (1.7 ± 10.1)	6.5 (5.6 – 7.4) (0.6 ± 6.5)
Toe PAT Reference ${\text{SP}}^{\text{i}}=141.9{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+{\text{SP}}^1$	9.1 (7.6 – 10.9) (2.1 ± 8.9)	6.2 (5.3 – 7.1) (0.4 ± 6.2)
Finger PPG Waveform Feature ${\text{SP}}^{\text{i}}=80.6{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+50.4\left({\text{b-time}}^{\text{i}}\right)+{\text{SP}}^1$	9.5 (7.9 – 11.5)*† (2.3 ± 9.3)	7.0 (6.1 – 7.7) (0.5 ± 7.0)
Ear PPG Waveform Feature ${\text{SP}}^{\text{i}}=30.2{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+26.2\left({\text{STT}}^{\text{i}}\right)+{\text{SP}}^1$ DPi = 30.6 (STTi) − 40.4(PWi) + DP1	9.5 (7.8 – 11.4)*† (0.7 ± 9.5)	5.7 (5.0 – 6.3)* (0.2 ± 5.7)
Toe PPG Waveform Feature ${\text{SP}}^{\text{i}}=141.9{\left(\frac{1}{\text{PAT}}\right)}^{\text{i}}+{\text{SP}}^1$	9.1 (7.6 – 10.9)* (2.1 ± 8.9)	6.5 (5.6 – 7.4) (0.2 ± 6.5)

^*denotes statistical significance (p < 0.05 with Holm’s correction for multiple comparison) versus baseline BP reference model (which predicts BP during the interventions simply via the baseline cuff BP measurement) and

^†denotes statistical significance versus corresponding pulse arrival time (PAT) reference model (which predicts the BP changes via 1/PAT alone). The demographic reference model (which predicts the BP changes via subject age, height, weight gender, and baseline cuff BP) did not offer value and was not compared. The models are shown only if they provided added value over reference models. Each feature (1/PAT, b-time, STT, and PW as defined in Fig. 3) actually represents the current feature minus the baseline feature divided by the baseline feature as shown in Fig. 4.