TABLE 2.

Mean, variance, and mutation rate calculations for data from Table 1

Strain and culture	Mean	Variance	Avg cells plated	Avg mutation frequency	Mutation rate (Poisson equation)
Wild-type E. coli B
Individual	31.5	3,793.3	3.23E+09	9.76E−09	3.08E−10
Batch	4.6	60.3	2.85E+09	1.62E−09	6.47E−10
ΔmutS strain
Individual	136.8	4,247.7	3.73E+09	3.66E−08
Batch	177.6	2,254.2	3.92E+09	4.53E−08