Fig. 2: Evaluation in the large-scale outpatient setting.
From: Monitoring long-term cardiac activity with contactless radio frequency signals
a Comparison of real-time inter-beat interval (RT-IBI) error. Our system achieves a 26.1 ms median RT-IBI error, while mmHRV and V2iFi achieve 168.3 ms and 151.6 ms median RT-IBI error, respectively. b Comparison of root mean square of the successive differences (RMSSD) error. RF-HRV achieves a 53.8 ms median RMSSD error, while mmHRV and V2iFi achieve 632.3 ms and 569.1 ms median RMSSD error, respectively. c Comparison of standard deviation of all normal R-R intervals (SDRR) error. RF-HRV achieves a 33.7 ms median SDRR error, while mmHRV and V2iFi achieve 419.4 ms and 377.5 ms median SDRR error, respectively. d Comparison of proportion of N-N intervals exceeding 50 ms (pNN50) error. RF-HRV achieves 11.1% pNN50 error, while mmHRV and V2iFi achieve 36.4% and 32.8% median pNN50 error, respectively. e–h The cumulative distribution function (CDF) plots of RT-IBI error, RMSSD error, SDRR error, pNN50 error. i The RT-IBI estimated by our system from three heartbeat abnormalities. n = 6,222 outpatient data points in box plots of a–h. Square, mean; minima, smallest non-outlier value; maxima, largest non-outlier value; center line, median; box bounds, upper and lower quartiles; whiskers, 1.5  × interquartile range, in box plots of a–d.
