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Overlap and the errors of plaque counting: II. The bias of the variance and the concealment of errors

Published online by Cambridge University Press:  15 May 2009

D. W. Howes  and
S. Fazekas de St Groth
D. W. Howes
Affiliation:
Viral Products Section, National Biological Standards Laboratory, Commonwealth Department of Health, Melbourne, Victoria, Australia
S. Fazekas de St Groth
Affiliation:
Division of Animal Genetics, Commonwealth Scientific and Industrial Research Organization, Sydney, New South Wales, Australia
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Summary

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The overlapping of plaques compresses their distributions and reduces observed variances. For a given distribution the reduction of the variance is substantially larger than that of the mean. To derive the error of a plaque assay from the assumption that the variance equals the mean may therefore lead to serious over-estimation of the precision of the assay.

Procedures for estimating the true error of plaque assays are developed, and their use is illustrated on experimental material.

Information

Type
Research Article
Information
Journal of Hygiene , Volume 67 , Issue 2 , June 1969 , pp. 335 - 342
Copyright
Copyright © Cambridge University Press 1969

References

Howes, D. W. (1969). Overlap and the errors of plaque counting. 1. The overlap biases of observed counts and their correction. J. Hyg., Camb. 67, 317.Google Scholar