PMID- 17994942 OWN - NLM STAT- PubMed-not-MEDLINE DCOM- 20080103 LR - 20071112 IS - 1539-3755 (Print) IS - 1539-3755 (Linking) VI - 76 IP - 4 Pt 1 DP - 2007 Oct TI - Estimator of a non-Gaussian parameter in multiplicative log-normal models. PG - 041113 AB - We study non-Gaussian probability density functions (PDF's) of multiplicative log-normal models in which the multiplication of Gaussian and log-normally distributed random variables is considered. To describe the PDF of the velocity difference between two points in fully developed turbulent flows, the non-Gaussian PDF model was originally introduced by Castaing [Physica D 46, 177 (1990)]. In practical applications, an experimental PDF is approximated with Castaing's model by tuning a single non-Gaussian parameter, which corresponds to the logarithmic variance of the log-normally distributed variable in the model. In this paper, we propose an estimator of the non-Gaussian parameter based on the q th order absolute moments. To test the estimator, we introduce two types of stochastic processes within the framework of the multiplicative log-normal model. One is a sequence of independent and identically distributed random variables. The other is a log-normal cascade-type multiplicative process. By analyzing the numerically generated time series, we demonstrate that the estimator can reliably determine the theoretical value of the non-Gaussian parameter. Scale dependence of the non-Gaussian parameter in multiplicative log-normal models is also studied, both analytically and numerically. As an application of the estimator, we demonstrate that non-Gaussian PDF's observed in the S&P500 index fluctuations are well described by the multiplicative log-normal model. FAU - Kiyono, Ken AU - Kiyono K AD - College of Engineering, Nihon University, 1 Naka-gawara, Tokusada, Tamura-machi, Koriyama City, Fukushima 963-8642, Japan. FAU - Struzik, Zbigniew R AU - Struzik ZR FAU - Yamamoto, Yoshiharu AU - Yamamoto Y LA - eng PT - Journal Article DEP - 20071008 PL - United States TA - Phys Rev E Stat Nonlin Soft Matter Phys JT - Physical review. E, Statistical, nonlinear, and soft matter physics JID - 101136452 EDAT- 2007/11/13 09:00 MHDA- 2007/11/13 09:01 CRDT- 2007/11/13 09:00 PHST- 2007/05/29 00:00 [received] PHST- 2007/08/16 00:00 [revised] PHST- 2007/11/13 09:00 [pubmed] PHST- 2007/11/13 09:01 [medline] PHST- 2007/11/13 09:00 [entrez] AID - 10.1103/PhysRevE.76.041113 [doi] PST - ppublish SO - Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Oct;76(4 Pt 1):041113. doi: 10.1103/PhysRevE.76.041113. Epub 2007 Oct 8.