Nonlinear Dynamics

, Volume 68, Issue 3, pp 431–444 | Cite as

Entropy measures for biological signal analyses

Original Paper


Entropies are among the most popular and promising complexity measures for biological signal analyses. Various types of entropy measures exist, including Shannon entropy, Kolmogorov entropy, approximate entropy (ApEn), sample entropy (SampEn), multiscale entropy (MSE), and so on. A fundamental question is which entropy should be chosen for a specific biological application. To solve this issue, we focus on scaling laws of different entropy measures and introduce an ensemble forecasting framework to find the connections among them. One critical component of the ensemble forecasting framework is the scale-dependent Lyapunov exponent (SDLE), whose scaling behavior is found to be the richest among all the entropy measures. In fact, SDLE contains all the essential information of other entropy measures, and can act as a unifying multiscale complexity measure. Furthermore, SDLE has a unique scale separation property to aptly deal with nonstationarity and characterize high-dimensional and intermittent chaos. Therefore, SDLE can often be the first choice for exploratory studies in biology. The effectiveness of SDLE and the ensemble forecasting framework is illustrated by considering epileptic seizure detection from EEG.


Approximate entropy Sample entropy Scale-dependent Lyapunov exponent Seizure detection 


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.PMB Intelligence LLCWest LafayetteUSA
  2. 2.Mechanical and Materials EngineeringWright State UniversityDaytonUSA
  3. 3.Affymetrix, Inc.Santa ClaraUSA
  4. 4.Department of Earth & Atmospheric SciencesPurdue UniversityWest LafayetteUSA

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