Robust and realistic approaches to carry-over

✍ Scribed by Stephen Senn; Dimitrios Lambrou

• Book ID: 101239487
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 132 KB
• Volume: 17
• Category: Article
• ISSN: 0277-6715
• DOI: 10.1002/(sici)1097-0258(19981230)17:24<2849::aid-sim955>3.0.co;2-o

✦ Synopsis

If the area of the experiment were kept constant and the replication increased by using smaller plots we should only gain in precision if, as abundant agricultural experimentation shows to be generally the case, the greater proximity of the smaller areas led to a greater similarity of the fertility of the soil. The practical limit to plot subdivision is set, in agricultural experiments, by the necessity of discarding a strip at the edge of each plot. The width of the strip depends on the competition of neighbouring plants for moisture, soil nutrients and light, and is independent of the size of plots. Consequently, as smaller plots are used, a larger proportion of the experimental area has to be discarded. R. A. FISHER, The Design of Experiments (pp. 60-61)

SUMMARY

The relationship between choice of model for carry-over and choice of efficient cross-over design is studied in particular with reference to two treatment designs in four periods and two sequences. The effect of model miss-specification is also examined. It is concluded that previous claims regarding efficient designs are not necessarily reasonable.