Pub. date: 2008 | Online Pub. Date: November 27, 2007 | DOI: 10.4135/9781412953948 | Print ISBN: 9781412928168 | Online ISBN: 9781412953948| Publisher:SAGE Publications, Inc.About this encyclopedia
Additive and Multiplicative Models
Additive and multiplicative models are two alternative approaches to modeling effect of risk factors on disease. In additive models, risk—or disease incidence—changes by some fixed amount when a risk factor is present. The statement ‘If you take up X, you will increase your risk of Y by 10%’ is an example of an additive model of risk. In contrast, multiplicative models represent the changes in risk as a proportion of the baseline risk. The statement ‘If you take up X , you will double your risk of Y ’ is an example of a multiplicative model ...