Published online by Cambridge University Press: 15 May 2009
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.