Objectives: Introduction Over View of System Analysis and Design
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| 6.6 Summary Analysis is the heart of the process. It is the key component of the first two phases of the cycle. In analysis the present system, the analyst collects a great deal of relatively unstructured data through interviews, questionnaires, onsite observations, procedures manuals, and the like. Requirements determination involves studying the current business system to find out how it works and where improvements should be made. Systems studies result in an evaluation of how current methods are working and whether adjustments are necessary or possible. These studies consider both manual and computer methods, they are not merely computer studies. The specific methods analysts use for collecting data about requirements are called fact – finding techniques. These include the interview, questionnaire, record inspections (onsite review) and observation. Analysts usually employ more that one of these techniques to help ensure an accurate and comprehensive investigation. Structured analysis is a set of techniques and graphical tools that allow the analyst to develop anew kind of system specifications that are easily understandable to the user. Analysts work primarily with their wits, pencil, and paper. Most of them have no tools. The traditional approach focuses on cost/benefit and feasibility analysis, project management, hardware and software selection and personnel considerations. In contrast, structured analysis considers new goals and structured tools for analysis. The first step is to draw a data flow diagram (DFD). The DFD was first developed by Larry Constantine as away of expressing system requirements in a graphical from this led to a modular design. A data dictionary is a structured repository of data about data. It offers primary advantages of documentation and improving analyst/user communication by establishing consistent definitions of various elements, terms and procedures. A decision tree sketches the logical structure based on some criteria. It is easy to construct, read, and update. A decision tree is a diagram that presents conditions and actions sequentially and thus shows which conditions to consider first, which second, and soon. It is also a method of showing the relationship of each condition and its permissible actions. A decision table is a table of contingencies for defining a problem and the actions to betaken. It is single representation of the relationships between conditions and actions. The pros and cons of the tools are • The primary strength of the DFD is its ability to represent data flows. It maybe used at high or low level of analysis and provides good system documentation. 6. The data dictionary helps the analyst simplify the structure for meeting the data requirements of the system. It maybe used at high or low levels of analysis, but it does not provide functional details, and it is not acceptable to many nontechnical users. 7. Structured English is best used when the problem requires sequences of actions with decisions. 8. Decision trees and decision tables are best suited for dealing with complex branching routines such as calculating discounts or sales commissions or inventory control procedures. Download 0.94 Mb. Share with your friends:
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