Decision Trees - zward/Amua GitHub Wiki

Node Types

Decision trees are comprised of 3 types of nodes:

  • Decision node Decision nodes define decision points in the model. These nodes indicate choices that are under your control.
  • Chance node Chance nodes define probability events in the model.
  • Terminal node Terminal nodes define the payoffs associated with model outcomes.

Node Attributes

  • Name: Each node can be given a name. Names do not have to be unique in the tree.
  • Probability: Chance nodes must have probabilities that sum to 1.0. The letter c or C is used to indicate a complementary probability (i.e. sums to 1.0).
  • Payoffs: Terminal nodes contain payoff values for each model dimension.
  • Costs: Intermediate costs (also called 'tolls') can be added to decision or chance nodes by clicking the cost button on the toolbar or pop-up menu. These costs are added to any payoffs that occur later in the branch, so negative numbers should be used to capture costs.
  • Notes: More information (ex: notes, citations/sources, etc.) about nodes can be entered in the notes pane at the bottom of the screen.

Tree Results

After the model is run the expected values for each branch will be displayed on the canvas to the right of each chance node . The number of individuals in the cohort who end up at the end of each branch will also be displayed to the right of each terminal node .