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Adjustment by Neighbouring Plots in Progeny Trials with Cocoa

Published online by Cambridge University Press:  03 October 2008

G. Lockwood
Affiliation:
Cocoa Research Institute, PO Box 8, Tafo-Akim, Ghana

Summary

In Ghanaian cocoa progeny trials plot values were adjusted by covariance on neighbouring plots. Standard errors of differences between progenies were usually reduced by 10% and often by over 20% when covariates were formed from the residuals of neighbouring plots and analyses were iterated using successive improved estimates of treatment effects to derive fresh residuals. The method gave larger reductions in error and was effective over a wider range of variates than adjusting on early growth data from interplanted temporary trees of a standard variety.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1980

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References

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