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the sales rep? If you did that, you would have a physical data flow, because you pictured bubble 1.0 as a person, place, or thing rather than as a function. That would be a mistake in constructing a logicalDFD.DQ 4-6Compare and contrast the purpose of and techniques used in drawing physical DFDs and logical DFDs.ANS.We draw physicalDFDs to depict a system’s entities—both internal and external—and to characterize the communications between those entities. We draw logicalDFDs to describe the functions—or information processing activities—performed by the system.We use the same symbols for drawing logical and physical DFDs. However, the way we use those symbols differs. In a physical DFD, the bubbles are labeled with the names of entities, whereas in a logical DFD, the bubble labels describe the functions being performed. In a physical DFD, the labels on the data flows and on the data stores are specific names that describe the method used for communicating and storing data, whereas in a logical DFD, those labels are generic descriptions or names that describe the data.DQ 4-7“If we document a system with a system flowchart and data flow diagrams, we have overdocumented the system.” Discuss fully.ANS.We don’t agree with this statement. Each tool depicts different aspects of a system and is used for different purposes.A systems flowchartdepicts a system’s information and operations activities (i.e., a business process) and superimposes those activities onto the organization’s structure. We use the flowchart to understand the system’s activities—both information and operations—and to analyze the system’s controls.Data flow diagramsconcentrate on the data, the entities that act on the data, and the information systems functions being performed by a system. We use the DFDs to analyze each of these elements of a system. Also, we use the logical DFD extensively in the development of new systems.DQ 4-8“Preparing a table of entities and activities as the first step in documenting systems seems to be unnecessary and unduly cumbersome. It would be a lot easier to bypass this step and get right to the necessary business of actually drawing the diagrams.” Do you agree? Discuss fully.
4Solutions for Chapter 4ANS.We don’t agree. With practice, preparation of a table of entities and activities is not difficult. Also, we find that we prefer to prepare this table before drawing any