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The Importance of Lay-out in Determining Error Variance in Field Experiments

Published online by Cambridge University Press:  03 October 2008

E. A. Roberts
E. A. Roberts
Affiliation:
Biometrical Branch, NSW Department of Agriculture, McKell Building, Rawson Place, Sydney, 2000, Australia
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Summary

Examples are taken from three biometrical texts, two unpublished experiments and Yates (1937) to illustrate quantitatively how the lay-out of the plots can affect the estimate of error variance in field experiments and how confounding of treatment and positional effects can arise. In two examples in which the plots did not run the whole length or width of the block, the estimates of error were reduced by one half and one quarter respectively by allowing for sub-blocks within blocks or for rows and columns. In split-plot experiments where the main plots were split breadthwise, the sub-plot error was about the same size as the main-plot error or larger whereas it is expected to be at most one third that of the main plots when these are split lengthwise. Serious bias can arise in the estimate of treatment effects due to confounding with positional effects; this is illustrated.

Type
Research Article
Information
Experimental Agriculture , Volume 21 , Issue 3 , July 1985 , pp. 223 - 232
Copyright
Copyright © Cambridge University Press 1985

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References

REFERENCES

Christidis, B. G. (1931). The importance of the shape of plots in field experimentation. Journal of Agricultural Science, Cambridge 21:14–37.CrossRefGoogle Scholar
Cochran, W. G. & Cox, G. M. (1957). Experimental Designs 2nd Edition. New York: Wiley.Google Scholar
Dyke, G. V. (1976). Comparative Experiments with Field Crops. London: Butterworth.Google Scholar
Fisher, R. A. (1935). The Design of Experiments. Edinburgh: Oliver & Boyd.Google Scholar
Gomez, K. A. & Gomez, A. A. (1984). Statistical Procedures for Agricultural Research 2nd Edition. New York: Wiley-Interscience.Google Scholar
Kempton, R. A. & Howes, C. W. (1981). The use of neighbouring plot values in the analysis of variety trials. Applied Statistics 30:59–70.CrossRefGoogle Scholar
Le Clerg, E. L., Leonard, W. H. & Clark, A. G. (1962). Field Plot Technique. Minneapolis, Minn.: Burgess.Google Scholar
Mead, R. & Riley, Janet (1981). A review of statistical ideas relevant to intercropping research. The Journal of the Royal Statistical Society Series A 144:462–509.CrossRefGoogle Scholar
Mead, R. & Stern, R. D. (1980). Designing experiments for intercropping research. Experimental Agriculture 46:329–342.CrossRefGoogle Scholar
Panse, V. G. & Sukhatme, P. V. (revised by Sukhatme, P. V. & Amble, V. N., 1978). Statistical Methods for Agricultural Workers, 3rd Edition. New Delhi: Indian Council of Agricultural Research.Google Scholar
Pearce, S. C. (1976). The conduct of ‘post-mortems’ on concluded field trials. Experimental Agriculture 12:151–162.CrossRefGoogle Scholar
Pearce, S. C. (1983). The Agricultural Field Experiment: A Statistical Examination of Theory and Practice. Chichester: Wiley-Interscience.Google Scholar
Snedecor, G. W. & Cochran, W. G. (1980). Statistical Methods 7th Edition. Ames: Iowa State College Press.Google Scholar
Wiebe, G. A. (1935). Variation and correlation in grain yield among 1500 wheat nursery plots. Journal of Agricultural Science, Cambridge 50:331–357.Google Scholar
Yates, F. (1937). The Design and Analysis of Factorial Experiments. Technical Communication No. 35. Harpenden: Imperial Bureau of Soil Science.Google Scholar
Yates, F. & Finney, D. J. (1955). Report to the Government of India on Statistics in Agricultural Research. FAO Report No. 358. Rome: Food and Agricultural Organisation of the United Nations.Google Scholar