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Decision Trees

Decision tree is a tree like structure that represents the various conditions and the subsequent possible actions. It also shows the priority in which the conditions are to be tested or addressed. Each of its branches stands for any one of the logical alternatives and because of the branch structure, it is known as a tree.

The decision sequence starts from the root of the tree that is usually on the left of the diagram. The path to be followed to traverse the branches is decided by the priority of the conditions and the respectable actions. A series of decisions are taken, as the branches are traversed from left to right. The nodes are the decision junctions. After each decision point there are next set of decisions to be considered. Therefore at every node of the tree represented conditions are considered to determine which condition prevails before moving further on the path.

This decision tree representation form is very beneficial to the analyst. The first advantage is that by using this form the analyst is able to depict all the given parameters in a logical format which enables the simplification of the whole decision process as now there is a very remote chance of committing an error in the decision process as all the options are clearly specified in one of the most simplest manner.

Secondly it also aids the analyst about those decisions, which can only be taken when couple or more conditions should hold true together for there may be a case where other conditions are relevant only if one basic condition holds true.

Decision Tree

In our day-to-day life, many a times we come across complex cases where the most appropriate action under several conditions is not apparent easily and for such a case a decision tree is a great aid. Hence this representation is very effective in describing the business problems involving more then one dimension and parameters.

They also point out the required data, which surrounds the decision process. All the data used in the decision making should be first described and defined by the analyst so that the system can be designed to produce correct output data.

Consider for example the discount policy of a saree manufacturer for his customers. According to the policy the saree manufacturer give discount to his customers based on the type of customer and size of their order. For the individual, only if the order size is 12 or more, the manufacturer gives a discount of 50% and for less than 12 sarees the discount is 30%. Whereas in case of shopkeeper or retailers, the discount policy is different. If the order is less than 12 then there is 15% discount. For 13 to 48 sarees order, the discount is 30%, for 49 to 84 sarees 40% and for more than 85 sarees the discount is 50%. The decision policy for discount percentage can be put in the form of a decision tree displayed in the following figure.

The decision trees are not always the most appropriate and the best tool for the decision making process. Representing a very complex system with this tool may lead to a huge number of branches with a similar number of possible paths and options.

For a complex problem, analyzing various situations is very difficult and can confuse the analyst.


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