Charles L. Webber, Jr., Ph.D.

Professor Emeritus
Department of Cell and Molecular Physiology
Stritch School of Medicine
Loyola University Chicago
Health Sciences Division
2160 South First Avenue
Maywood, IL 60153 USA

RECURRENCE QUANTIFICATION ANALYSIS (RQA) is a powerful analytical tool developed over the last decade for the study of nonlinear dynamical systems. RQA is the necessary extension of recurrence plot analysis (RPA), a more qualitative tool. Since RQA metholology is independent of limiting constraints such as data set size, data stationarity, and assumptions regarding statistical distributions of data, RQA seems ideally suited for physiological systems characterized by non-homeostatic transients, state changes, and noise from within and without the organism or process. Mathematical details and the physiological utility of RQA are described in numerous papers with Joseph P. Zbilut, Ph.D., DNSc of Rush University (deceased Jan. 10, 2009).