(41C) Estimating Viral Concentrations from Dilution Counts:

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An extract from Estimating Viral Concentrations from Dilution Counts: a reliable computation method programmed on a pocket calculator, Ph, Rcwssel and Jocelyne Husson, Journal of Virological Methods, 34 (1991), 113-140.

Summary
A program for a Hewlett-Packard 41C calculator is described, applying the maximum likelihood method for the estimation of the density of a suspension of infective particles when counts are available for a number of independent dilutions of the original suspension. An unbiased estimate for the variance of the density, a suitable confidence interval and its corresponding confidence level are also given by the program. Moreover, after testing for the presence of overcrowding and/or clumping, the selection of suitable dilutions is fully automated so as to avoid recourse to statistical tables…
Conclusion
Although the method presented has been in existence for several years, it has not found wide application yet. The HP-41C program is a fully automated implementation of the method, without recourse to statistical tables for the significances of the tests used. The appropriate selections are made by the program, and the results displayed accordingly. The data entered are stored by the program in accumulated form, which allows for analysis of the data at different significance levels. This, and the portability of the HP-41C system, should stimulate its application.

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