Estimation of ke0 from raw data

Hi, I have a data set containing PK concentrations and PD effect. When plotting PD as a function of PD a clear anti-clockwise hysteresis plot appears. I would like to get a (rough) estimate of the PD time delay w.r.t. the PK without using a compartmental description for the observed PK, even not using a polynomal function that fits the PK. The assumption I make is that all PD delay can be explained by the delay through an effect compartment. I am wondering if methods exist that solely use the raw data to calculate such time delays. Thank you for any comment/suggestion, Jos Jos Lommerse Modeler Consultant Quantitative Solutions BV Molenweg 79 5349 AC Oss The Netherlands [email protected]<mailto:[email protected]> +31 412 211102 Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (2000 Galloping Hill Road, Kenilworth, New Jersey, USA 07033), and/or its affiliates Direct contact information for affiliates is available at http://www.merck.com/contact/contacts.html) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system.