Chapter 12 Systems Analysis and Design

Chapter 12 - Systems Analysis and Design The main aim of the system analysis and designed is to create and effectively use a system. System analysis and designed: System: collection of activities and elements organized to accomplish a goal. Information system: collection of hardware, software, people, procedures, data, and the internet. These works to provide information essential to running an organization This information: 1- produce a product or service. 2- Derive profit. The organization has an information flows into and within it , so this flows must follow a route that is defined by a set of rules and procedures to avoid confusion. From time to another, the organization needs to change its information system, because of the organizational growth, mergers and acquisitions, new thinking opportunities, revisions in governmental regulations, and availability of new technology. System analysis and design (system life cycle) : is a six-phase problem solving procedure for examining and improving system. The phases are the follow: 1- Preliminary investigation. 2- System analysis. 3- Design. 4- Development. 5- Implementation. 6- Maintenance. This six-phases used by computer professionals known as system analysts. System analysts: studies an organization's systems to determine what actions to take and how to use computer technology to assist them. Why many managers are learning to do these activities themselves? Because when you go to seek expert you will discover that the system analysts are so overworked, it will take them 3 years to get to your request. (And this will give you skills to solve a wide range of problems. ) Phase 1: preliminary investigation Proposed project to determine the need for new information system *requested by end user or the manager The system analysts or the end user concerned with 3 tasks: 1- Briefly defining the problem: examining whatever current information system is in use. / determine what information is needed. ** If the information system is large: it's done by analysts. Small: it's done by end user. 54 2- Suggesting alternative system: to suggest some possible plans as alternative to present arrangement. 3- Preparing short report: (in large project: the system analyst writes report summarize (the result / schedule for development /and recommendation of the project)) , this report is presented to higher management then management decides whether to finance to the second phase. ** if you're the end user, you might not produce a written report, you might report your finding directly to your supervisor . Phase 2 : the system analysis : Here we are concerned with determine the requirement for new system –not with designGathering data: -Data obtained from observation and interviews or from questionnaires. - Studying documents that describe formal lines of authority and standard operating procedures. (e.x: organization chart : shows levels of management as well as formal lines of authority.) Analyzing the data: The idea is to learn how info currently flows and why it is not flowing appropriately. Apply logic to the existing arrangement to see how workable it is. - - * There is many tools helps analysts and end users in the analysis phase , such as : (BACK TO FIGURES IN PAGES 308-310) 1 – Top down analysis method: identify the top-level components of a complex system; each component is then broken down into smaller and smaller components. 2 – Grid charts : shows the relationship between input and output documents. 3- System flowchart: show the flow of input data to processing and finally to output or distribution of information. 4- Data flow diagram: show the data or information flow within an information system. 5- Automated design tools: (also called computer-aided software engineering (CASE) tools) software packages that evaluate hardware and software alternative according to requirements given by the systems analysts - Also used in system design and development as well. - It is relieve the systems analysts of many repetitive tasks, develop clear documentation and for larger projects, coordinate team member activities. 55 Documenting systems analysis: System analysis stage is typically documented in report for higher management. This report describes the current information system, the requirement for new system, and a possible development schedule. Management studies the report and decides whether to continue with the project and move to phase 3. Phase 3 : system design Consists of three tasks : 1- Designing alternative systems : System designer evaluate each alternative system for feasibility. Feasibility means : 1 – economic feasibility : costs 2- technical feasibility: reliable . 3operational feasibility: actually operate and resist . 2- Selecting the best system: When choosing the best design, managers must consider these four questions: (1) will the system work with the organization's overall information system? (2) Will the system be flexible enough so it can be modified in the future? (3) Can it be made secure against unauthorized use? (4) Are the benefits worth the costs? 3- Writing the systems design report : Prepared for the higher management and describes the alternative designs. Present costs versus the benefits and outlines the effect of alternative designs on the organization. It usually concludes by recommending one of the alternatives. Phase 4: system development : It has three steps : 1- acquiring software: application software for the new system can be obtained in two way, 1) purchased as off-the-shelf packaged software and possibly modified, 2) can be custom-designed. 2- acquiring hardware : When the new system require new computer system, the equipment needed and the places where they are to be installed must be determined. And this can be tremendously expensive proposition. 3- testing the new system : after installing the software and equipment, the system should be tested, sample data is fed into the system, the processed information is then evaluated to see whatever result are correct. And when you find any problem using the system you improve it, then it will be ready to use. 56 Phase 5 : system implementation(conversion) It’s the p o ess of ha ging-converting-from the old system to the new one and training people to use the new system. * Types of conversion There are four approaches to conversion: 1- Direct approach: abandoning the old and starting up the new. This can be risky because if anything is still wrong with the new system, the old one is no longer available to fall back on. So any problem might be catastrophe. 2- Parallel approach: old and new systems are operated side by side until the new one proves to be reliable. This is low risk, if the new system fails, the organization can just switch to the old one. Keeping enough equipment and people active to manage two systems at the same time can be very expensive. So this is used only in cases in which the cost of failure or of interrupted operation is great. 3- pilot approach, tried the new system in only one part of the organization, once the system is working smoothly in that part, its implemented throughout the rest of the organization. It is less expensive and riskier; however, the risks can be controlled because problems will be confined to only certain areas of the organization. 4- phased approach: the new system I implemented gradually over a period of time, the entire implementation process is broken down into parts or phases, and begin with the first phase to the last one This is an expensive proposition because the implementation is done slowly, and its one of the least risky approach. The pilot and the phased are the favored methods: Pilot: preferred when there are many people in an organization preforming similar operations, Phased: more appropriate for organizations in which people are preforming different operations. *Training : its one of the most overlooked activities 57 Phase 6 : systems maintenance Most organizations spend more time and money on this phase than on any of the others. It has two parts: system audit and a periodic evaluation. 1- Systems audit: the system's performance is compared to the original design specifications, to determine whether the new procedure are actually furthering productivity, if they are not some redesign may be necessary. 2- Periodic evaluation: all systems should be evaluated from time to time to determine whether they are meeting the goals and providing the service they are supposed to. Two alternative approaches that require much less time in following the 6 phases: 1- Prototyping: to build a model or prototype that can be modified before the actual system is installed. 2- Rapid application development (RAD): involves the use of powerful development software, small specialized teams, and highly trained personnel. Phase Preliminarily investigation System analysis System design System development System implementation System maintenance Activity Define problem, suggest alternatives, prepare short report. Gather data, analyze data, document Design alternative, select best alternative, write report. Develop software,acquire hardware, test system. Convert,train. Preform systems audit , evaluate periodically. 58