“…Time-and frequency-domain HRV indices are vulnerable to artifacts, missing data, temporal factors, and trends in RR intervals (Kim et al, 2009(Kim et al, , 2007Spiers, et al, 1993;Task Force, 1996), and are thus highly influenced by decisions for data reduction, artifact detection and removal, and technical specifications (e.g., digital filtering, sampling frequency, detector or interpolation algorithms, windowing; Kim et al, 2009;Task Force, 1996;Welch, 1967).…”