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Journal of Theoretical Medicine
Volume 2 (2000), Issue 2, Pages 73-80

Calculating Summary Measures of Unimodal Response Curves by Means of Nonlinear Regression Models

Department of Metabolic Diseases and Nutrition, Heinrich-Heine-University of Düsseldorf, P.O. Box 10 10 07, D-40001 Düsseldorf, Germany

Received 10 March 1998; Accepted 8 January 1999

Copyright © 2000 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In biomedical research summary measures such as the curve maximum (Cmax)are frequently used to describe and analyze unimodal response curves. However, if the true curve is perturbed by autocorrelated noise the calculation of summary measures from raw data can be arbitrary and misleading due to high peaks produced by the correlated errors. A possible solution is to fit suitable nonlinear functions to the response curves and estimate the summary measures from these functions. In this paper formulas are derived providing a way to estimate important summary measures of unimodal curves by means of the parameters of the lognormal function. The method is illustrated by application to pharmacodynamic data.