Some Investigations on Orthogonal Arrays

In this paper we obtain some results on orthogonal arrays (O-arrays) of strength six by considering balanced arrays (B-arrays) of strength six with \(\underline{\mu}’ = (\mu – 1, \mu, \mu, \mu, \mu, \mu, \mu – 1)\) which we call Near O-arrays. As a consequence we demonstrate that we obtain better bounds on the number of constraints for some O-arrays as compared to those given by Rao (1947).