Table 2 Descriptions of measures
| Â | Abbreviation | Description |
|---|---|---|
Nonlinear variables | ||
 NOLDS software package [49] | ||
  Detrended fluctuation analysis | DFA | Long-range correlation of the physiological time series |
  Sample entropy | SampE | Irregularity of physiological time series without self-matches |
  Hurst exponent | HurstE | Long-term memory processes of a time series |
  Lyapunov exponent | LyapE | Chaotic or periodic properties of a time series |
 EntroPy (https://github.com/raphaelvallat/entropy) | ||
  Permutation entropy | PermE | Information content of a given time series based on probability distribution of a set of continuous points |
  Spectral entropy | SpecE | Degree of skewness in the frequency distribution |
  Singular value decomposition entropy | SVDE | Dimensionality of a time series. |
  Approximate entropy | AppE | Regularity of times series fluctuations |
  Higuchi fractal dimension | HFD | Self-similarity in time series using increasingly distanced samples in time |
  Katz fractal dimension | KFD | Complexity and self-similarity in time series using consecutive time points |
 Lempel-Ziv complexity reference [50] | ||
  Lempel Ziv complexity | LZC | Randomness of finite sequences |
Linear variable | ||
 SciPy signal processing [51] | ||
  Power | Power | Frequency amplitude of oscillations in a time series |