Some design-problems in crop experimentation .3. nonorthogonality

Pearce, S.C. (1995) Some design-problems in crop experimentation .3. nonorthogonality. Experimental Agriculture, 31 (4). pp. 409-422. ISSN 0014-4797. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Ideally each block of an experiment should be made up in the same way with respect to treatments, that is, the design should be 'orthogonal'. In practice that can be difficult to achieve, especially if the blocks have been chosen to fit the fertility pattern of the field. Sometimes it is impossible, in which case each block will have to contain its own selection of treatments. A number of simple and useful possibilities exist. Whatever non-orthogonal design is chosen some of the contrasts of interest (perhaps all of them) will be evaluated less efficiently, but that can be compensated by the smaller error mean-square given by a better blocking system. Also, where blocks do differ in their content, comparing their means will provide additional information about treatment effects. Sometimes the information may be worth the trouble of recovery. Special attention is given in this paper to total balance (including balanced incomplete block designs), supplemented balance, square and rectangular lattices and alpha-designs. The reinforcement of a design is explained and the advantages considered.

Item Type: Article
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Mathematics Statistics and Actuarial Science
Depositing User: O.O. Odanye
Date Deposited: 28 May 2009 17:16
Last Modified: 16 Jul 2014 10:58
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