shows the predicted risk of SBI for children with and without SBI using each of the models. Using dichotomized values for heart rate, a patient either has an 11.7% (tachycardia absent) or a 14.4% (tachycardia present) risk of SBI. Risks of SBI were 10.7% and 14.7% for dichotomous values (absent and present, respectively) of respiratory rate. Models including continuous values (models 2-6) showed a wider range of predicted risks (Fig. 1, as indicated by the dotted lines) and better discriminative ability.