Markov Models

A decision analysis problem is attacked using a formal process that begins with constructing a mathematical model. For more than 40 years, the decision tree has been the most common formalism, comprising choices, chances, and outcomes. The modeler arranges near-term events in a tree structure, and attempts to balance realism and attendant complexity with simplicity. In problems that lead to long-term differences in outcome, the decision model must have a definite time horizon, up to which the events are characterized explicitly. At the horizon, the future health of the patient or cohort must be summed and averaged into “subsequent prognosis.” For problems involving quantity and quality of life, where the future natural history is well characterized, techniques such as the declining exponential approximation of life ...