Comput Biol Med. 2000 Jul;30(4):237-45.  

A new method to determine a fractal dimension of non-stationary biological
time-serial data.

Shono H, Peng CK, Goldberger AL, Shono M, Sugimori H.

Department of Obstetrics and Gynecology, Saga Medical School, 5-1-1 Nabeshima,
Saga 849-8501, Japan. shonoh@post.saga-med.ac.jp

We devised a new analysis using quartile deviation of integrated and subtracted
fluctuation, termed QIS-A, to determine a fractal dimension of non-stationary
fluctuation. In the algorithm, computations of the quartile deviation, Q(n), of
all integrated and subtracted fluctuations are repeated over all scales (n). The
fractal scaling exponent is determined as a slope of the line relating log Q(n)
to log n. Comparison of the QIS-A and a spectral analysis using 20
computer-simulated fractional Brownian motions demonstrates robustness of the
QIS-A to non-stationary fluctuations.

PMID: 10821941 [PubMed - indexed for MEDLINE]