Table 2.

Feature list and description

Feature	Notation elsewhere	Description
x1	$A_{cc}^R$	R-wave Detection Accuracy [26]
x2	ρ	Correlation-based Periodicity
x3	${\overline{s}}_{bw}$	BW check [26]
x4	${\overline{s}}_{hf}$	Relative amplitude of HF noise [26]
x5	μs	Mean
x6	σs	Standard Deviation (STD)
x7	β1	Skewness
x8	β2	Kurtosis
x9	${\overline{\sigma }}_{qrs}$	Relative STD of QRS [26]
x10	SPI	Spectral Purity Index [37]
x11	H(s)	Sample Entropy
x12	${\overline{p}}_{bw}(s)$	Relative Power of the BW [26]
x13	${\overline{p}}_{qrs}(s)$	Relative Power of the QRS [26]
x14	${\overline{e}}_{qrs}(s)$	Relative energy of QRS [26]
x15	${\overline{f}}_c(s)$	Central Frequency
x16	MS–QI	ECG Quality Index [15]