Hostname: page-component-78c5997874-8bhkd Total loading time: 0 Render date: 2024-11-03T05:40:39.508Z Has data issue: false hasContentIssue false

The errors of long-term experiments

Published online by Cambridge University Press:  27 March 2009

H.D Patterson
Affiliation:
A.R.C. Unit of Statistics, University of Edinburgh
Bridger I. Lowe
Affiliation:
Rothamsted Experimental Station, Harpenden, Herts.

Summary

Yield (or other variate) values from crops recurring on the same plots in long-term experiments are subject to correlations known as serial plot correlations. Neglect of these plot correlations can result in loss of efficiency in the estimation of treatment effects and bias in the estimation of error.

Serial plot correlations are calculated from 12 experiments on arable crops in England and Wales, for yields 4, 6 or 8 years apart. They are usually positive, with average value 0·2. In one set of experiments the losses in efficiency caused by plot correlations of this magnitude are shown to be small, but some of the biases in the estimates of error are large. Biases in the variances of treatment means can be wholly or partly eliminated by separating two components of error, plot error and plot x year error.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1970

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Cochran, W.G. (1939). Long-term agricultural experiments. Jl R. statist. Soc. (Suppl.) 6, 104–48.Google Scholar
Patterson, H.D. (1953). The analysis of the results of a rotation experiment on the use of straw and fertilizers. J. agric. Sci., Camb. 43, 7788.CrossRefGoogle Scholar
Patterson, H.D. (1959). The analysis of a nonreplicated experiment involving a single four-course rotation of crops. Biometrics 15, 3059.CrossRefGoogle Scholar
Patterson, H.D. (1964). Theory of cyclic rotationc experiments. Jl R. statist. Soc. B, 26, 145.Google Scholar
Shrader, W.D., Fuller, W.A. & Cady, F.B. (1966). Estimation of a common nitrogen response function for corn (Zea mays) in different crop rotations. Agron. J. 58, 397401.CrossRefGoogle Scholar
Yates, F. (1954). The analysis of experiments containing different crop rotations. Biometrics 10, 324–46.CrossRefGoogle Scholar