Observed and expected distributions of <i>RT</i>⁺ revertants in RT_IN and RT_SUB bursts.

aSets of 10 and 5 independent experiments were conducted with RTSUB and RTIN, respectively. Because no significant differences were found in the observed distributions of revertants among the experiments of each set (G-test of independence, P = 0.3414 and P = 0.1103, with 16 and 27 df for the set of experiments conducted with RTIN and RTSUB, respectively), the results of all the experiments comprising each set were pooled. bExpected distributions of revertants were inferred using the p0 method, based on the fraction of plates displaying no revertants [47]. cP values represent the probability that the observed distributions fit the Poisson distributions as determined by G-tests for goodness-of-fit. See text for details.