Recent developments in nonregular fractional factorial designs

Nonregular fractional factorial designs such as Plackett-Burman designs and other orthogonal arrays are widely used in various screening ex- periments for their run size economy and flexibility.The traditional analysis focuses on main effects only. Hamada and Wu (1992) went beyond the tra- ditional approach and proposed an analysis strategy to demonstrate that some interactions could be entertained and estimated beyond a few sig- nificant main effects. Their groundbreaking work stimulated much of the recent developments in optimality criteria, constructionand analysis of non- regular designs. This paper reviews important developments in nonregular designs, including projection properties, generalized resolution, generalized minimum aberration criteria, optimality results, construction methods and analysis strategies.