Journal of quality technology vol:34 issue:4 pages:422-436
When performing an experiment in a time sequence, the experimenter may have reason to believe that the observed responses will be influenced by a temporal trend over the course of the experiment. This paper presents an algorithm for the construction of blocked designs that are optimally balanced for time trends. Cost considerations are allowed for in the construction process. Cost-efficient and trend-resistant run orders are constructed for regression designs in the presence of either fixed or random block effects. The proposed algorithm is intended to provide the experimenter with a general method for solving a wide range of important problems. Examples clarify practical utility, and show that the computed trend-resistant run orders have outstanding performance in terms of both cost and D-optimality.