Fig. 8
Bland–Altman plots of the inter-examiner variables from the frequency domain and nonlinear analysis. Bland–Altman plots (mean difference [bias] and 95% limits of agreement [upper and lower]). HRV: heart rate variability; VLF: very-low frequency; LF: low-frequency band; HF: the high-frequency band; ms2: milliseconds squared; n.u: normalized units; log: logarithmic; LF/HF: ratio of LF-to-HF; SD1: Poincaré plot standard deviation perpendicular the line of identity; SD2: Poincaré plot standard-deviation along the line of identity; SD2/SD1: ratio of SD1-to-SD2; ApEn: approximate entropy; SampEn: sample entropy; DFA α1: detrended fluctuations analysis, which describes short-term fluctuations; DFA α2: detrended fluctuation analysis, which describes long-term fluctuations.
