Fig. 1. Log-likelihood profiles for the parameters of the Fixed C50^OHierarchical model, expressed as a percentage of the estimated value. The horizontal line  represents the significance level on a chi-square distribution (P = 0.025). Note that the profiles of the C50^Hfor the four stimuli are almost the same. IIV = interindividual variability; TLAR = tolerance to laryngoscopy; TLMA = tolerance to laryngeal mask airway insertion; TOSS = tolerance to shaking and shouting; TTET = tolerance to tetanic stimulation.