Statistical Application of Orthogonal Arrays

Rao (1947) introduced orthogonal arrays because of their desirable statistical properties when used in “fractional factorial” experiments. Nowadays the main statistical application of orthogonal arrays, with mixed levels or otherwise, is still as fractional factorials, although other applications have been discovered. We will present the main application in considerable detail, while only giving key references for the other applications. Unless stated otherwise, throughout this chapter the term orthogonal array is to be interpreted as including mixed level arrays.