Decision tree descriptions of calculations. (1) Decision tree cost = the sum of all pathway costs (2) Cost of an event = the sum of (the unit costs of all resources utilised by the event multiplied by the volume of resources utilised) (3) Probability of a pathway = (pE1 × pE2 ... xpEI ... xpEn) where EI = eventI, and n = the total number of events in the pathway (4) Cost of a pathway = the sum of the cost of all events in pathway (5) A decision tree enables a method of modelling, in chronological order, all possible events (6) Resources = consultations, medicines, and transport, E = event, p = probability (7) ● = Chance node which has a branch for each possible outcome or event. Each event ha s an associated probability and value. (8) ◀= End node which does not have any succeeding braches. Each end node returns a probability and a value for the associated pathway. Upper value = probability of reaching the end point of the pathway. Lower value = cost incurred in reaching the end point of the pathway.