Abstract
SUMMARY: When the technique of saturation mapping is employed to estimate the number of loci in a distinct chromosomal region, there is always the possibility that some loci will not be detected. If the number of mutants per locus follows a Poisson distribution, the number of mutationally silent loci can be estimated. This paper describes a method for fitting such data to a Poisson distribution truncated at the zero class and a method for estimating the number of mutationally silent loci. The use of these methods is demonstrated by their application to some published data.