Abstract: This paper deals with optimality aspects of complete block designs with interference effects arising from the neighbouring units up to distance 2 (first and second order) from one side. Conditions have been obtained for the block design to be universally optimal for estimating direct and interference effects. Some classes of balanced and strongly balanced complete block designs have been identified to be universally optimal for the estimation of direct effects, first order neighbour effects and second order neighbour effects.
Keywords: Block design, interference, neighbouring units, left circular, strongly balanced