Fig. 1. A sample distribution of minimum alveolar concentration (MAC) values determined in 500 replicate simulated experiments is shown. The range of MAC values in these 500 replicates is 0.63%, the mean is 0.99%, and the SD is 0.084%. Assumptions used in these simulations: population MAC = 1.0%; interindividual variability = 10% of population MAC; incremental changes for inhaled anesthetic = 20% of starting concentration; machine measurement error = 5%; ventilation/perfusion mismatch = 0.1%; starting concentration = 1.3% inhaled anesthetic.