A Method for estimating long-range power law correlations from the electroencephalogram

Paul A. Watters, Frances Martin

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Recent research has found long-range electroencephalogram (EEG) power law correlations, indicating time scale invariance. However, the EEG is also rather noisy, displaying short-term decorrelation like white noise—i.e., what is scale invariant at one time period may disappear in the next. The paradoxical combination of short-divergence, but long-range correlations, suggests that any long-range correlations detected in one sample may be spurious, since they could be related to amplitude fluctuations. To overcome this problem, this paper suggests a new technique for analysing EEG signals segmented by zero-crossings, using detrended fluctuation analysis (DFA), evaluated across two time periods (TIME) and different sites (SITE). A mean scaling exponent across all subjects and sites of α=0.67 was observed. MANOVA analysis indicates no significant main effect for TIME or interaction with SITE, suggesting that the zero-crossing method may be successful in determining the fractal nature of EEG dynamics across relatively long time scales.
Original languageEnglish
Pages (from-to)79-89
Number of pages11
JournalBiological Psychology
Issue number1
Publication statusPublished - 2004
Externally publishedYes


  • EEG
  • zero-crossing
  • DFA


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