37.1 What is a State Transition Diagram?

State transition diagrams provide a simpler representation of a Markov model than decision trees. While they do not display the level of detail found in a decision tree (i.e., events, probabilities, and rewards), state transition diagrams clearly show the transitions among health states. Even in complex Markov models, where the decision tree is far too large to fit on a single printed page, the corresponding state transition diagram is almost always small enough for simple reproduction and efficient communication.

The design of a state transition diagram is subject to a number of guidelines. Here are the basic ones:

• "States" that represent health status.

• "Arcs" that represent transitions between any two states.

The combination of states and arcs represent the possible movements of a patient from one health state to another over the entire course of the model time frame.