Objectives: Introduction Over View of System Analysis and Design
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| 6.4.3.2 Using Decision Trees Developing decision trees is beneficial to analysts in two ways. First of all, the need to describe conditions and actions forces analysts to formally identify the actual decision that must be made. It becomes difficult for them to overlook and integral step in the decision process, whether it depends on quantitative or nonquantitative variables. It is possible, for instance, to show what discount action to take, depending on the number of dollar spent by customers. When an organization opens accounts with dealers and suppliers, it formalizes an agreements for taking discounts from the full invoice price. Two conditions are specified in this agreement first, the invoice must always be paid within ten days of its receipt, and, second, the size of the discount will depend on the value of the invoice. It is agreed that under some conditions the organization can take the action of deducting a 3 percent discount under other conditions, a 2 percent discount and under all other conditions, no discount is allowed. Within 10 days Longer than 10 days Over $ 10,000 $ 5,000 to $ Below $ Take 3% discount from invoice Take 2% discount from invoice total Pay full invoice amount Decision trees also force analysts to consider the sequence of decisions. Consider the sequence of decision in the example. you can quickly determine that one condition is amount of the invoice-does not matter unless another condition is met and the invoice is paid within the time established by the supplier – ten days. The other conditions are relevant only if that condition is true. Therefore, the decision tree identifies the time condition first and shows two values (within ten days and longer than ten days. The discount condition is described next, but only for the branch of the tree for WITHIN TEN DAYS. The LONGER THAN TEN DAYS branch has no other relevant conditions and so show the resulting action (unconditionally. This tree shows that the action PAY FULL INVOICE AMOUNT applies under two different conditions. It also shows implicitly that there is no reason to pay invoice of less than $5,000 within ten days, since there is no discount available for these amounts. The decision tree shows the nonquantitative conditions for processing accounts payable signed invoice, authorized purchase, and correct pricing. Depending on the set of conditions that exist, one of two actions can betaken payment can be authorized or the submitted invoice can be rejected. Notice how clearly each alternative is shown in the decision tree. Sometimes in more complex business situations, the specific action most appropriate under several conditions is not readily apparent without formal analysis of this nature. Analysts find that in accounts payable processing, it is necessary to determine whether a purchase order is available and valid and whether the invoice is processed properly before it is actually paid. In turn, they must learn of the conditions for proper invoice processing. Full development and examination of the decision tree also shows clearly that there are only two ways an invoice can be authorized for payment but many conditions under which payment can be rejected. The sequence of decision is easy to see in this example. The condition of having a valid purchase order does not matter unless the invoice has been signed. The signature is important, since the condition of having a signed invoice must be met before processing can continue. Then analysts can consider the authorization condition. Download 0.94 Mb. Share with your friends:
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