Scientific Publications by FDA Staff

Environmetrics 1992;3(3):319-34

Box-cox transformation in the analysis of combined effects of mixtures of chemicals

Razzaghi M, Kodell RL

A new general approach to modelling the joint action of two non-interactive toxicants is considered. It is shown that the proposed method provides a more refined characterization of a mixture of two chemicals. The method is based on using the Box-Cox power transformation to derive the most suitable function of concentration to be used in a linear response function obtained from a linearizing transformation. The concepts of concentration and response additivity as two extreme cases of additive joint action are discussed and used to demonstrate the ideas of an ¿envelope of additivity¿. Two examples are used to provide further illustration of the proposed approach.