Non-linear mixed-effects models

Authored by: Marie Davidian

Longitudinal Data Analysis

Print publication date:  August  2008
Online publication date:  August  2008

Print ISBN: 9781584886587
eBook ISBN: 9781420011579
Adobe ISBN:


 Download Chapter



In many applications, particularly in the biological sciences, the time course of a continuous response for an individual may be characterized by a function that is non-linear in one or more parameters, where an “individual” may be a human subject, an animal, a plant, an agricultural plot, a laboratory sample, or other observational unit. The non-linear function may be chosen on empirical grounds for its ability to represent faithfully the apparent individual-specific response-time relationship. For example, the logistic growth model, discussed in Section 5.2.1, is often adopted for this reason to describe the S shape, typical of relationships between continuous measures of growth and time on a given plant or plot. Alternatively, a non-linear model for individual behavior may arise from theoretical, mechanistic considerations that are of central scientific interest. In pharmacokinetics, as we demonstrate in Section 5.2.2, non-linear models for drug concentrations achieved over time following administration of a drug are derived from representing the body as a system of “compartments,” embodying assumptions on how processes of drug absorption, distribution, and elimination take place within a subject.

Search for more...
Back to top

Use of cookies on this website

We are using cookies to provide statistics that help us give you the best experience of our site. You can find out more in our Privacy Policy. By continuing to use the site you are agreeing to our use of cookies.