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Sometimes we are faced with a situation, for which there is no clear solution. We are stuck. A decision tree is a tool to help us get our thinking back in order and enable us to discern a clear set of options and weigh the values of each option.


  1. Download and read the document: Deciding-in-Messy-Situations
  2. Form a team and collectively select an issue where the team is “limping along. In other words, she is unable to choose between one option and the other.
  3. On the left, write the name of the decision on a large piece of paper and on the right, write the different options. It helps if the diagram you are about to draw is methodically drawn from left to right. The idea is for the team to map out the decisions with the associated consequences in the diagram.
  4. Evaluate the decisions have mapped out evaluate the decision paths and discover the criteria you are going to use for assigning value and probability. (Also, don’t ignore the following options: make no decision, make a different decision, or let someone else make the decision.
  5. From time to time, reconsider the name of your decision. Sometimes the decision itself evolves as you consider the options.
  6. There are only a few ways a decision tree can go wrong. One is to ignore the rule that options must be mutually exclusive. For example, deciding which of several options to try first (a mutually exclusive approach to options) will work much better than deciding on the best order to try the options (where options are not mutually exclusive).
  7. In unclear situations, the first option will generate new information and understanding. This changes the circumstances of the decision about what to do. Calculations can also go wrong. Always check that the probabilities of all decisions combined are 100%. Check the calculations of an expected value for each decision with an uncertain outcome.
  8. Decision trees provide “answers,” but are especially good to use when drawn with the specific intention of ordering thoughts rather than representing “reality” and really figuring out what to choose. Using the diagram as an exploration allows you to “interrogate” the diagram, making ideas and assumptions visible.

Download document: Deciding in Messy Situations 


Learning to use systems thinking in decision-making processes.

Learning Outcomes

Decision trees to understand and analyze the options we face in making good decisions.


A large sheet of paper, markers

Download and read


Review the drawn decision tree with students. Do they find it a useful addition to making a mind map. Do they see where a decision tree is different from a mind map? Do they think a decision tree can help them with future decisions?


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