Table 4.

Standardized Correlation Coefficients (r) for Correlation of PSG ECG or ActiGraph Link-Derived Features, With Features Derived From the Wearable Devices Under Study

Device	Mean of vector magnitude (Apple Watch) or motion seconds (Oura Ring)	SD of vector magnitude (Apple Watch) or motion seconds (Oura Ring)	Mean of IBI	SD of IBI	RMSSD of IBI
Apple Watch	0.83 (0.08)	0.79 (0.08)	0.92 (0.04)	0.76 (0.09)	0.58 (0.18)
Oura Ring	0.53 (0.16)	0.47 (0.13)	0.85 (0.14)	0.78 (0.15)	0.62 (0.17)

Values within each cell represent the mean and SD across nights. IBI, interbeat interval.