Estimating viral concentrations: a reliable computation method programmed on a pocket calculator

A method has been developed, based on the Newton-Raphson iterative procedure, for calculating the concentration of viral suspensions from the dose-response data yielded by the cytopathic effect assays. The computation method provides the maximum likelihood estimate with its 95% approximated confidence limits, and determines the value of chi 2 for testing the goodness of the fit. A program for a Hewlett-Packard 41C calculator is presented which is suitable to most experimental situations.