A1964
Title: Exact designs for order-of-addition experiments under a transition-effect model
Authors: Jiayi Zheng - George Mason University (United States) [presenting]
Nicholas Rios - George Mason University (United States)
Abstract: In the chemical, pharmaceutical, and food industries, the order of adding a set of components sometimes impacts the final product. These instances of the Order-of-Addition (OofA) problem seek to find the optimal sequence of components. Extensive research on this topic has been conducted, but almost all designs are found by optimizing the D-optimality criterion. However, when prediction of the response is important, I-optimal designs remain necessary. Furthermore, designs are needed for experiments where some orders are infeasible due to constraints. A new model for OofA experiments is presented that uses transition effects to model the effect of order on the response. Three algorithms are proposed to find D- and I-efficient exact designs under this new model: Simulated Annealing, a metaheuristic algorithm; Bubble Sorting, a Greedy local optimization algorithm; and the Greedy Randomized Adaptive Search Procedure (GRASP), another metaheuristic algorithm. These three algorithms are generalized to handle block constraints, where components are grouped into blocks with a fixed order. Two examples illustrate the effectiveness of the proposed designs and models, even under block constraints.
