Table 8. Overview of the results of studies assessing SDNN, RMSSD, and pNN50 derived from rPPG signals equal to or less than 60 s.

ICC, inter-correlation coefficient; MAE, mean absolute error; ME, mean error; r, correlation coefficient.

Study	PRV metric	Result
Huang & Dung (2016)	SDNN	MAE = 0.49–3.79 (static); MAE = 2.08–28.87 (motion)
	RMMSD	MAE = 0.09–7.97; MAE = 10.29–50.04 (motion)
	SDNN	r = 0.9750, ICC = 0.9491, MAE = 3.49 (stationary)
		r = 0.9896, ICC = 0.9766, MAE = 2.65 (motion)
Melchor Rodriguez & Ramos-Castro (2018)	RMSSD	r = 0.9791, ICC = 0.9208, MAE = 7.13 (stationary)
		r = 0.9463, ICC = 0.8898, MAE = 7.81 (motion)
	pNN50	r = 0.9350, ICC = 0.8996, MAE = 8.65 (stationary)
		r = 0.9204, ICC = 0.8560, MAE = 7.80 (motion)