1. Measures of Complexity

2. Information theory estimates
Algorithmic complexity
Hidden Markov

3. Approximate entropy
Probability that 2 sequences which are similar for m points, remain similar at the next point

4. Anaesthesia depth discrimination from EEG data, deeper anaesthesia means lower complexity
Characterization of mentally pathological and healthy groups from EEG recordings
Discrimination of different stages of sleep from EEG and respiratory motion, lower complexity during deep sleep

5. Sample entropy
Modification of approximate entropy and self-matches exclusion

6. Neonatal sepsis prediction from HRV data

7. Fourier entropy Compute PSD of a time series
Normalize spectrum to get probability-like distribution
Calculate entropy of normalized spectrum

8. Wavelet entropy Compute wavelet spectrum of a time series
Calculate wavelet entropy

9. Wavelet entropy of pigs ECG

10. Renyi entropy Compute time-frequency representation of a time series
Count connected regions above some threshold
One peak in time-frequency space represents an elementary event
Counting peaks gives an estimate of complexity

11. Higher order methods Break a time series into parts
Compute entropy of each part
Treat entropy values as a time series and compute entropy of that sequence

12. Multiscale methods Downsampling of a time series
Calculate entropy of downsampled data

13. MSE entropy of HRV signal