This paper presents (i) philosophical issues concerning the use
of systematic designs; (ii) a review of the current knowledge
concerning existence and construction of (nearly) trend-free
designs for varietal trials, with or without blocking; and
(iii) algorithms to obtain (nearly) trend-free designs as
described in (ii). An important message of the paper is that
efficient algorithms are now available, enabling users to
obtain good designs without any difficulty.
Copies of preprints are available from the author upon request. Use the preprint number (located at the top of the page) and make the request directly to the author, Iowa State University, Department of Statistics, Snedecor Hall, Ames, IA 50011-1210.