Table 4. Agreement statistics of the natural logarithm of SDNN and RMSSD for the different recordings compared to the gold standard.

	SDNN				RMSSD
	Pearson’s correlation (95% CI)	Bias (95% CI)	95% LoA	Cohen’s d (95% CI)	Pearson’s correlation (95% CI)	Bias (95% CI)	95% LoA	Cohen’s d statistics (95% CI)
10s recording1	0.758 (0.744–0.772)	0.416 (0.403–0.429)	-0.362–1.193	0.894 (0.879–0.910)	0.853 (0.843–0.862)	0.096 (0.085–0.106)	-0.525–0.716	0.161 (0.141–0.181)
10s recording2	0.764 (0.750–0.778)	0.398 (0.385–0.411)	-0.386–1.181	0.855 (0.839–0.871)	0.862 (0.854–0.871)	0.079 (0.069–0.089)	-0.533–0.691	0.150 (0.132–0.181)
10s recording3	0.760 (0.746–0.774)	0.406 (0.393–0.419)	-0.386–1.198	0.873 (0.858–0.889)	0.858 (0.849–0.866)	0.090 (0.080–0.101)	-0.528–0.709	0.171 (0.130–0.170)
Avg10s	0.863 (0.855–0.872)	0.406 (0.397–0.416)	-0.131–0.944	0.874 (0.859–0.890)	0.941 (0.937–0.945)	0.088 (0.082–0.095)	-0.282–0.459	0.167 (0.153–0.189)
30s recording	0.859 (0.850–0.868)	0.240 (0.231–0.249)	-0.300–0.780	0.516 (0.501–0.532)	0.932 (0.928–0.937)	0.055 (0.048–0.061)	-0.343–0.453	0.104 (0.086–0.121)
120s recording	0.956 (0.953–0.959)	0.064 (0.059–0.069)	-0.222–0.349	0.137 (0.122–0.153)	0.986 (0.985–0.987)	0.014 (0.011–0.017)	-0.166–0.194	0.027 (0.009–0.044)

CI: confidence interval; LoA: limits of agreement; s: seconds; Avg10s: the average of the measurements from the three 10s recordings