(A) Respiratory droplet SAR and (B) direct contact SAR. To assess the impact of binomial uncertainty in ferret SAR estimates, we simulated 1000 datasets by taking binomial samples from each data point. Here, the binomial probability for each was given by the observed SAR and the number of trials was the number of ferrets used. To introduce binomial uncertainty into those experiments with an SAR of 0 or 1, we set the binomial probability to 0.1 or 0.9, respectively. The solid line is the average model fit to all of the simulated datasets and is nearly identical to that in Figure 3. Dashed lines give the 97.5 and 0.025 percentiles of the upper and lower bounds, respectively, of the 95% confidence intervals on model predictions from each of the simulated datasets. These indicate much more uncertainty in model predictions across datasets that generates a larger equivocal region of ferret SARs than observed in Figure 3. However, values of ferret SAR indicative of subcritical and supercritical strains still exist, indicating that our qualitative results are robust to binomial uncertainty.