Rao’s Inequalities and Improvements

If the other parameters of an orthogonal array are specified, there is a limit on the number of possible factors, imposed by the defining conditions. We shall discuss these restrictions in this chapter and in Chapter 4. Section 2.2 presents the celebrated inequalities found by Rao (dy1947). Section 2.3 discusses improvements on Rao’s bounds for orthogonal arrays of strength two and three. Results on improvements for arrays of general strength are contained in Section 2.4, while Section 2.5 pays special attention to orthogonal arrays in which all the factors are at two levels.