Growing a Decision Tree is an iterative process. If the tree becomes too complex you trim it, if it is too simple you grow it another branch. This process allows you to share your knowledge and it forces you to think about certain decisions you take and how to formalize them.
When you navigate a Decision Tree -especially one you haven’t grown yourself- always keep in mind the reason behind the existence of the branches. Don’t just blindly follow branches, because it is part of the tree.
They’ve been around for some time now. Here’s an example decision tree from an Harvard Business Review article dating back to the 1960s, 1964 to be exact:
I find them an interesting tool to organize my thoughts and think about how I come to a decision. Note that some branches grow from your decisions, while others are rooted in choices made outside your control.
Here’s a great Prezi-presentation on Decision Trees.