Modified non-sequential third order rotatable designs constructed using Pairwise Balanced Design

The technique of fitting a response surface design is useful in modelling of experimental designs. Response surface is used in situations where the response of interest is influenced by several experimental variables. The objective of fitting a response surface design is to reduce cost of experimentation and to obtain optimal designs. The property of rotatability is a desirable quantity of experimental design and requires the variance of the fitted design to be constant on circles or spheres about the centre of the design. In this article, a construction technique of fitting modified non-sequential third order rotatable design (TORD) using Pairwise Balanced Design (PBD) is presented. The variance function of a third order response surface design and the properties of Pairwise Balanced Design are utilised for the construction.