Table 3.

Correlation coefficients between the results generated by smartphone PPG and ECG.

Threshold	FPDT	rMSSD	pNN50	SDNN	log HF	log LF	Avg. (FPDT)	Avg. (SPQI)
SPQI > 0	Peak	0.520	0.652	0.692	0.639	0.607	0.622	0.669
	Valley	0.608	0.731	0.791	0.758	0.741	0.726
	M1D	0.596	0.675	0.823	0.790	0.807	0.738
	M2D	0.290	0.559	0.489	0.549	0.475	0.472
	Tangent	0.615	0.752	0.864	0.843	0.858	0.786
SPQI > 0.8	Peak	0.604	0.715	0.786	0.699	0.678	0.696	0.758
	Valley	0.702	0.834	0.879	0.844	0.842	0.820
	M1D	0.705	0.777	0.915	0.846	0.882	0.825
	M2D	0.393	0.665	0.626	0.629	0.536	0.570
	Tangent	0.756	0.848	0.947	0.900	0.936	0.877
SPQI > 0.95	Peak	0.689	0.768	0.847	0.799	0.749	0.770	0.843
	Valley	0.898	0.911	0.967	0.914	0.934	0.925
	M1D	0.795	0.851	0.943	0.881	0.892	0.872
	M2D	0.565	0.800	0.802	0.762	0.632	0.712
	Tangent	0.879	0.923	0.974	0.939	0.954	0.934
All correlation coefficients in the table have p < 0.05