Universally optimal designs under an interference model with equal left- and right-neighbor effects

In this paper, the interference model with equal left- and right-neighbor effects is considered. We base this work on the method of Kunert and Martin (2000) to give a sufficient condition for universal optimality of circular neighbor designs. We show that some of neighbor designs by Rees (1967), Azaïs et al. (1993) and Druilhet (1999) satisfy this condition.