The statistical analysis of autoradiographs II. Theoretical aspects including methods for optimal allocation of measurement effort

Under carefully controlled conditions autoradiographic grain densities vary in accordance with the Poisson distribution. The present paper derives several different formulae and presents graphs to enable the experimenter to measure such grain densities to any specified accuracy after making the appropriate correction for radioactive background. Emphasis is placed upon the allocation of counting effort between one or more labelled sources and the unlabelled background so that the total area of emulsion to be counted is minimized. This technique of optimal measurement allocation has been considered for grain-density measurements both by visual counting and by photometric methods. This approach has also been applied to the problem of accurately determining the percentage of labelled cells by sampling from a large population.