Extracting model equations from experimental data

This letter wants to present a general data-driven method for formulating s uitable model equations for nonlinear complex systems. The method is valida ted in a quantitative way by its application to experimentally found data o f a chaotic electric circuit. Furthermore, the results of an analysis of tr emor data from patients suffering from Parkinson's disease, from essential tremor, and from normal subjects with physiological tremor are presented, d iscussed and compared. They allow a distinction between the different forms of tremor. (C) 2000 Elsevier Science B.V. All rights reserved.