Methods for comparing mutation rates using fluctuation assay data

Comparing microbial mutation rates via the fluctuation assay protocol is an important routine task in the laboratory. However, methods for the comparison of mutation rates are still scarce and not well understood. This paper proposes new methods to address this situation. First, it provides a likelihood ratio test. Second, it explores the use of confidence intervals that can be readily computed. Third, it uses simulations to assess the new and existing methods. Both the likelihood ratio test and the use of confidence intervals were found to be superior to the general-purpose Mann-Whitney test, while the t-test was found to be unsuitable for fluctuation assay data. In addition, the method based on confidence intervals is suitable for comparison of experiments in which the terminal cell population sizes differ.