Journal of statistical planning and inference vol:124 issue:1 pages:231-249
When experiments are to be performed in a time sequence, the observed responses may be affected by an unknown time trend. Run orders that are optimally balanced for time trends usually involve huge costs due to the large number of factor level changes. Therefore, trend-free run orders can be of low practical value in view of economical considerations. Tack and Vandebroek (J. Statist. Plann. Inference 98 (2001) 293) recently presented a design algorithm to construct trend-resistant run orders that give maximal information per unit cost. In this paper, the latter approach is extended to the construction of trendresistant run orders for which the total cost has to be lower than a specified budget. A new design algorithm is proposed that offers the experimenter a general method for solving a wide range of practical design problems. (C) 2003 Elsevier B.V. All rights reserved.