Tight 4-factor orthogonal main effect plans Original Research Article

Our main result is a determination of those parameter sets for which a tight OMEP with four rows exists. These are used to characterize those n for which an s1 × s2 × s3 × s4//n OMEP exists. The main application of this is a method for determining the minimal n for which an s1 × s2 × s3 × s4//n OMEP exists. We use the same techniques to give an algorithm for determining the minimal n for which an s1 × s2 × s3 × s4//n OMEP with equal replication exists. More importantly, the methods used here can be applied to OMEPs on any number of factors.