A method for evaluating a hospital patient's risk of mortality includes collecting data from physiologic signals generated by patient monitors, physiologic signals of organ function, and demographic information for a patient. A measure of the variability of at least one of the physiologic signals is determined. Data and the measure of variability are analyzed to determine whether a value for a particular physiologic or demographic variable falls within a critical interval for the variable that indicates that the value is predictive of mortality or survival. Each time a value for a physiological or demographic variable for the patient falls within a critical interval, the occurrence of an event for the patient is recorded. The number of events for the patient is counted over a time period. Output perceptible by human user that indicates the patient's risk of mortality or likelihood of survival is generated based on the count.