Table 4.

Maximum likelihood estimates of mutational parameters for the combined G27 + G33 25°C data set, under a model assuming a γ distribution of mutational effects

β	U	E(a)	Fit	P
→∞	0.024  (0.010–0.047)	0.096  (0.061–0.140)	−2.2	<0.05
2	0.029  (0.012–0.060)	0.078  (0.045–0.140)	−0.2	>0.5
1	0.039  (0.018–0.080)	0.059  (0.034–0.110)	0.0	>0.9
0.5	0.060  (0.027–0.120)	0.040  (0.023–0.076)	0.0	>0.9
0.25	0.100  (0.045–0.200)	0.024  (0.013–0.049)	0.0	>0.9

β, shape parameter; U, mutation rate per haploid second chromosome per generation; E(a), average effect of mutations. Maximum-likelihood estimates of U and E(a) are given for the fixed values of β indicated, with two log-likelihood support limits (analogous to 95% confidence intervals) in parentheses. Fit is measured as the difference in log-likelihood from the best fitting model. Probabilities <0.05 indicate poor fit of the given β.