Name: Donato M. Galleon III Discussion Questions #5

IT 193 - Systems Analysis & Design

Chapter 5: Data and Process Modeling

1. Describe data and process modeling, and name the main data and process modeling techniques.

Data and process modelling uses a variety of techniques to represent an information system and processes and data flow contained within the information system. Methods of data and process modelling can include DFD's (Data Flow Diagrams), object modelling and entity-relationship diagrams. (https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

2. Describe the Gane and Sarson symbols used for processes, data flows, data stores, and entities. Give four examples of typical names for processes, data flows, data stores, and entities. http://www.softtester.org/portfolio/cis244/assignment8.html

3. What is the relationship between a Context Diagram and Diagram 0, and which symbol is not used in a context diagram?

A context diagram is a top-level view of an information system that shows the boundaries and scope of the system, whereas a diagram 0 is a DFD that depicts the first level of detail below the initial context diagram and shows major processes, data flows and data stores as well as repeating the external entities and data flows that appear in the context diagram. Data stores are not shown in the context diagram because they are contained within the system and remain hidden until more detailed diagrams are created. (https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

4. What is meant by an exploded DFD?

An exploded DFD has a higher-level diagram called the parent diagram, and a lower-level diagram that is referred to as the child diagram. In this sense, a diagram 0 is a child diagram of a context diagram because diagram 0 is a more detailed or exploded view of process 0 on the context diagram.( http://www.softtester.org/portfolio/cis244/assignment8.html)

5. Describe a data dictionary and give examples of how and when it is used.

A data dictionary, also known as a data repository, is a central storehouse of information about a system’s data that also defines all data elements and meaningful combinations of data elements (also known as a data item) within the system. Data dictionaries are typically used by a systems analyst to collect, document and organize specific facts about the system including the contents of data flows, data stores, entities and processes. (https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

6. Explain the DFD leveling technique.

Leveling is a technique used to show more detail in lower-level or child diagrams. Leveling is done by drawing a series of increasingly detailed diagrams until the desired degree of detail is reached. (http://www.softtester.org/portfolio/cis244/assignment8.html)

7. What is a balanced DFD?

DFD balancing ensures that the input and output data flows of the parent DFD are maintained on the child DFD in order to maintain consistency between the parent and child DFD’s. (https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

8. Describe the steps in creating a decision table.

a) Place a heading at the top left that names the table. b) Enter the conditions under the heading, with one condition per line, to represent the outcomes. c) Enter all potential combinations of Y/N (for yes and no) for the conditions. Each column represents a numbered possibility called a rule. d) Place an X in the action entries area for each rule to indicate a decision on an action http://www.softtester.org/portfolio/cis244/assignment8.html

9. Discuss the pros and cons of decision tables versus decision trees.

Decision tables often are the best way to describe a complex set of conditions. Many analysts use decision tables because they are easy to construct and understand, and programmers find it easy to work from a decision table when developing code. Decision trees show the logic structure in a horizontal form that resembles a tree with the roots at the left and the branches to the right. Like flowcharts, decision trees are useful ways to present the system to management. Decision trees and decision tables provide the same results, but in different forms. Whether to use a decision table or decision tree often is a matter of personal preference. A decision table might be a better way to handle complex combinations of conditions. On the other hand, a decision tree is an effective way to describe a relatively simple process. (https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

10. What is Structured English?

Structured English is a subset of standard English that describes logical processes clearly and accurately, and when used must conform to the following rules:

• Use only the three building blocks of sequence, selection and iteration. • Use indentation for reliability. • Use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules.
(https://ict108businessinformatics.wikispaces.com/Questions+Week+5)

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