Table 2.
Descriptions of measures
| 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 |