A decision tree is a tool for choosing between several courses of action. You can craft a decision tree using paper and pencil, but multiple software programs give the power to do it on the computer. If you want to make your decisions on a Mac, there are open-source programs you can use to form decision trees and carry out the calculations to compare different outcomes.
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To make a decision tree, first write down the decision you have to make, then draw a line from the decision to each of your options. If you're considering a new product line, for instance, the options might be to launch the new product; offer an upgrade of your current products; or make no changes. Each option generates further alternatives -- if you do decide to launch a new line, you have to choose the timing -- so add those branches to the tree. The tree is done when the tips of the branches show every foreseeable outcome.
Using the Tree
Once you've identified all the possible outcomes, assign a value to each, It could be a cash value -- how much your salary increases if you get a Ph.D., for instance -- or a numerical score to represent increased opportunities or job satisfaction. If some outcomes are uncertain, assign them a probability, with the total probabilities of all options adding up to 100 percent. By multiplying the value of each option by its probability, you determine which result looks like the best bet.
There are a number of decision-tree applications on the market, but not all are open-source. Creators of an open-source software make its code freely available so that others can spot and fix bugs and come up with improvements on the original code. DTree Jungle is an open-source decision-making program that runs on Mac OS X. XMind, which is an open-source application for brainstorming and "mind mapping," includes the capacity to create decision trees.
Decision-tree software not only helps with personal and business decisions, it works in the classroom for training students in decision-making concepts. If you don't like the open-source programs available, there are other affordable alternatives. For example, you can use Microsoft Word's drawing functions to create a decision tree in Word, though you'll have to calculate the value of the different alternatives by hand, instead of having the computer do it.