When level changes and trend-resistant effects are considered in factorial experiments, the order of experimental runs is essential. Under such considerations, it is helpful to use orthogonal arrays to arrange experimental runs and their orders simultaneously. To use this method, one needs to derive the level changes and trend resistance in the columns of the arrays to gain an appropriate order. Most research on this topic has focused on the case of symmetric factorials or only on the construction of trend-resistant run orders of asymmetric factorials. Recently, Wang (Statist. Sinica, 6 (1996) 471-479) derived the level changes and trend resistance in the columns of asymmetric orthogonal arrays for 2(m)4(n) factorial plans. In this article, we extend Wang's results to general asymmetric orthogonal arrays. (C) 1998 Elsevier Science B.V. All rights reserved.
