Fluctuation analysis: the effect of plating efficiency.

This paper supplements an earlier paper which explained how to calculate the probability distribution of the number of mutants that would be observed in a fluctuation test experiment. The formulas in that work give the distributions to be expected under a wide variety of experimental conditions, but the method it uses when only a fraction of the mutants will produce visible colonies are clumsy and inefficient. Here I describe efficient procedures for dealing with that case, provided that the mutation rate per cell division remains constant during the experiment.