Optimal designs for the proportional interference model

TL;DR

This paper develops optimal circular designs for the proportional interference model in block experiments, providing theoretical foundations and practical tools for estimating treatment effects with neighbor interference.

Contribution

It introduces Kiefer's equivalence theorems for the proportional interference model and connects optimal designs for directional and undirectional models.

Findings

Kiefer's theorems are extended to the proportional interference model.

Connections between directional and undirectional models are established.

A framework for computer-aided design optimization is provided.

Abstract

The interference model has been widely used and studied in block experiments where the treatment for a particular plot has effects on its neighbor plots. In this paper, we study optimal circular designs for the proportional interference model, in which the neighbor effects of a treatment are proportional to its direct effect. Kiefer's equivalence theorems for estimating both the direct and total treatment effects are developed with respect to the criteria of A, D, E and T. Parallel studies are carried out for the undirectional model, where the neighbor effects do not depend on whether they are from the left or right. Moreover, the connection between optimal designs for the directional and undiretional models is built. Importantly, one can easily develop a computer program for finding optimal designs based on these theorems.