System Analysis & Design - 2
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The document discusses the systems analysis and design process for developing systems like a Management Information System (MIS). It describes the key stages in the systems development life cycle, including problem recognition, feasibility study, systems analysis, design, testing, implementation, and maintenance. It provides details on various techniques and considerations used at each stage, such as classifying problem types during problem recognition, assessing technical, operational, and economic feasibility, gathering requirements, and designing system components. The iterative nature of systems development is also emphasized.
System Analysis & Design - 2
- 1. Gagan Deep Rozy Computech Services 3rd Gate, K.U., Kurukshetra-136119 [email protected]
- 2. To develop a systems, such as Management Information System (MIS), A General Business System, we need to carry out a detailed systems analysis and design activity. For this purpose, we shall have an overview of various stages in this process. System development follows an iterative process that recycles through each stage and almost all stages overlap each other. This is also termed as the System Life Cycle. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 3. SYSTEMS ANALYSIS AND DESIGN PROCESS The complete process of systems analysis and design may be considered as consisting of following phases Recognition of problem (Initial Investigation) : What is the problem or opportunity? Feasibility study : What are the user’s needs? What are the benefits? How can the problem be redefined? System analysis : What must be done to solve the problem?, What are the facts? System design : How must the problem be solved?, What is system flow? System testing : How ready are programs for test? Implementation : What is the actual operation? Maintenance: Should the system be modified? Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 4. RECOGNITION OF PROBLEM The first stage of any project, sometimes called the preliminary assessment, is a brief investigation of the system under consideration to provide to any project team. The idea of developing a new system occurs to the user when he recognizes that he has a problem with the means by which he currently carries out his business. This awareness marks the beginning of the recognition of problem phase, as almost all computer systems replace an existing system. A problem is well defined very rarely. It crops out with a vague feeling such as too much delay in order processing, or ‘We must reduce inventory cost by any means’ or ‘the existing calculation system is highly error prone’. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 5. A system analyst’s first task is to obtain more crucial information by interviewing and meeting concerned people. This will clarify how the problem was felt, how often it occurs, how it affects the business and which departments are suffering with this. Analyst does not do detailed investigation at this stage but he tries to define the scope of the problem, classifies it and measures its complexity to ensure that the problem is important and real enough to require further investigation. A proper understanding of the problem and its classification enables the systems analyst to separate symptoms from the real causes It also helps the analyst to consider it as a systems problem rather than a business problem and there by increasing the chances of success in proposing solutions. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 6. Following are the major classification of the problems: The existing system is slow and cannot respond to information i.e. problem of responsiveness. In this case the analyst will look to (i) find out present level of responsiveness and factors contributing to it and (ii) consider what changes or additions in existing procedures or resources, utilization would improve responsiveness and how such changes affect the organization. Originating workload is higher than the volume of workload handled i.e. problem of throughput. Here the analyst concentrates on finding the level of productiveness, its contributing factors, which further facilitates to improve productivity by better utilization of resources of by modifications to methods & resources. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 7. The present services are very expensive i.e. problem of economy. The management intentions could be (i) to reduce cost for same productivity (ii) to increase productivity but at present cost level of (iii) discontinue unproductive operations. Problem of Occurrence/ Reliability : At first, the analyst checks operations, step by step, to see when and how errors creep up & how to restrict these errors by using various clarification checks. For reliability, the system may have to be designed without any ambiguity and must be foolproof, as system failures result in loss of business. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 8. There is a problem of information, where the analyst would be concerned with organization of available information, its accessibility for decision making. These types of problems have close relationship with the ways of data storage and organization. Problem of efficiency. This problem is interrelated to all the above problems. The analyst must create a proper balance between all the contributing factors like response time, workload volume, cost of processing, and information needs etc. Problem of security of information : Here the analyst tries to devise controls over accessibility of information. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 9. FEASIBILITY STUDY If the Study proposal is accepted by management, it will lead to an investigation of the existing system or problem area, conducted in close collaboration with user management and in sufficient depth to establish in broad terms the technical, operational and economic feasibility of proposal. Having recognised the problem areas, the next step is to carry out an overall analysis of the system requirements in terms of its : The Input data Type of processing needed and The output reports This needs a detailed feasibility study to be carried out by the System Analyst. To carry out the analysis of the existing system the system analyst may take the help of any of the following techniques: Interviews Questionnaires Observation Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 10. This would help him to have an in-depth study of the existing system and understand its strengths and weakness and the requirements of the new proposed system. Three phases of feasibility study is used are as follows: Technical feasibility Operational feasibility Economic feasibility. The technical feasibility is concerned with the available hardware and software resources whether they meet the given requirements of the analysed system or not. It may also invoke the study of new alternatives to solve the given problem. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 11. The operational feasibility is to take the operational staff into confidence. The success of a good system depends upon the willingness of the operating staff. They should not have any fears like uncertainty about their jobs or control over the working which develops a bias in their minds towards the computerised systems. This acts as a big barrier in the successful implementation of any project. The economic feasibility deals with the study of cost benefit analysis. All the costs of the new proposed system are compared with the benefits which can be obtained for the management approval. The benefits may be quantitative or qualitative in nature. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 12. The following steps are used in the complete feasibility study: Study the existing system Define the scope of the proposed system Study the strengths and weakness of the existing system Study various alternatives Carry out feasibility studies Get the management approvals Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 13. SYSTEM ANALYSIS Detailed investigation should be conducted with personnel closely involved with the area under investigation, according to the precise terms of recognisation of problem arising out of the feasibility study report. The objectives at this stage are to provide solutions to stated problems, usually in the form of a specification to meet the users’ requirements; and to make recommendations for a new computer-based system. Analysis is an iterative and progressive process, examining information flows and evaluating various alternative design solutions until a preferred solution emerges. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 14. It involves an in-depth study of the existing system with to the following : Organization structure Sources of data origination flow of data within the organization Accuracy and timeliness aspect of the data handling process. The process of data storage The type of data processing The reports being generated at various stages The new user requirements Estimation of resources needed to design the new system Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 15. SYSTEM DESIGN System design is a creative as well as a technical activity. This stage is the most time and resource consuming. It is the real technical activity which involves the design of the system around the computer. It includes many steps such as : The preparation of system outlines chart Design of input forms, validation procedures and data preparation procedures Design of output reports Code designing Detailed file layout and file designing Selection of system software and selection of programming languages or database to be used Computer procedure design Program development Testing of the programs Security and Controls Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 16. SYSTEM TESTING This phase involves the testing of overall system. First, it test the parts separately and finally the system as a whole. Each subsystem or independent module and program is tested first and then through the interfaces to other subsystems the complete system is tested. This is the most important phase as the system analyst has to get the user certification for the accuracy of the system. In other words, it may also be referred as the acceptance testing by the user. Such a testing should be carried out by the user, the users representative, the system analyst, the standards group, the external systems auditor or any combination thereof. The test data is normally prepared by the user to check for all possible combination of correct data as well as the wrong data which should be trapped by the system and reported as an error. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 17. IMPLEMENTATION Implementation is concerned with those tasks leading immediately to a fully operational system. It involves programmers, users and operations management, but its planning and timing is a prime function of systems analysis. After the system has been certified by the user, it comes to the stage of implementation. It involves many issues like preparation for the change over to the new system and then the actual change over. Preparation of the site and installation of the facilities, training of the staff, Preparation of data files etc. are the various steps involved which might require the involvement of the system analyst, the user as well as the operational management. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 18. Changeover : After all the preparations for the system implementation are completed, comes the stage of actual changeover. This involves the usage of new system which has been developed and thoroughly tested. Some of these changeover approaches are as given below. Direct Changeover Parallel Running Pilot Running Direct Changeover :In this method, the old system is scrapped or withdrawn the moment new one is put into use. For example if it is a Banking System, this type of changeover would mean that the manual record keeping is stopped and is directly handled through the new computerized system. This could lead to some problems if the new system does not behave as expected. This may be the result of some unforeseen situations which had not been taken care of during the system analysis and design phase. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 19. Parallel Running : Parallel running is a method of submitting a new system to a final acceptance test, in which data is processed using both the old and new systems simultaneously. The result of two systems are compared and any discrepancies examined to see whether the computer system is at fault. The main drawback of this method is extra cost because the user staff will have to work with two systems i.e. old and new. Pilot Running : Pilot running is an alternative to parallel running, and consists of the allocation of a certain amount of work to be performed by the computer while the remainder is done by old method. The amount of work performed on the computer is gradually increased until the changeover is complete and the old system is discontinued. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 20. MAINTENANCE Once the system has settled down and been running for some time, the systems analyst may be involved in amendment procedures to adapt the system to changing conditions; in auditing the system to check that the stated objectives of the system are still valid in the present environment; and in evaluating the achievement of those objectives. This is an ongoing exercise after the system has been implemented. The real life would is never static. Its requirements and objectives keep changing. So shall be the system which have been designed primarily to meet those objectives. Thus the system analyst has to keep on carrying out changes and modification into the system, a stage called normally as system maintenance. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 21. As shown in figure (next slide), system development follows an iterative process that recycles through each stage and almost all stages overlap each other. This is also termed as the SYSTEM LIFE CYCLE. It is in the nature of system that they share a common life cycle pattern. After a system has been in operation for a number of years, it gradually decays and becomes less and less effective because of the changing environment to which it has to adapt. For a time it is possible to overcome problems by amendments and minor modifications to the system but eventually it will be necessary to acknowledge the need for fundamental changes. At this stage the systems analyst becomes involved and investigates the problems and the requirements have been adequately identified, a new system can be designed and subsequently implemented. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 22. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 23. PRINCIPLES OF SYSTEM DESIGN There are some of the do’s and dont’s that help in designing an effective system. Some of these are : Principle of modular design : The system should be broken down into smaller parts and then each part shall be designed as a separate module. this help in paying equal attention to all parts rather than neglecting one and over attending another. Principle of sub system integration : The modules designed separately need to be integrated in a unified whole to provide synergetic effect only the proper integration will lead to effective working of system. Principle of minimum information : A good system should be designed in a way that supplies minimum amount of information required for decision making to the user as any additional amount of information will burden the system for resources. However, if any additional information is required for better decision making, system should provide for it through query system which supplies information on demand rather than on routine basis. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 24. Principle of user based design : The system should be user friendly. It should not be rigid to supply only fixed information but should be flexible enough to give information to satisfy users. Principle of manager-analyst co-operation : Manager is the user of information. On the other hand Analyst is the person responsible for the design of MIS. The two often fail to understand each other’s requirements and come into conflict. A good design require the active co-operation of both for which they might have to for go their biases. Principle of cost effective design : Cost effectiveness is the most important criterion for any system, if a system cost exceeds its benefits, it will be of no use. For this purpose we will do a cost benefit analysis. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 25. SYSTEMS ANALYSIS TOOLS The first and obvious purpose of a system analyst’s work is to establish precisely What the system is intended to achieve? What information enters it, leaves it and is held within it? Only when he knows to what objectives a system is directed, and in a position to change or replace it. The second purpose is to enable him to communicate with management at all levels, so that the findings of his investigations can be confirmed and possible changes discussed on the basis of common knowledge. The third purpose is to design the system i.e. enter into system design stage. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 26. Now we are discussing a few tools which can be used to establish these requirements of a system analyst’s job. Graphical Tools Organisation Chart Fact Finding Interviews Questionnaires Observations Data Dictionary Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 27. PROS AND CONS OF SYSTEM ANALYSIS TOOLS Which tool is the best depends on a number of factors: the number and complexity of the problem, the number of actions resulting from the decisions, and the ease of use. In reviewing the benefits and limitations of each tool, we come to the following conclusions: The primary strength of the DFD is its ability to represent data flows. It may be used at high or low levels of analysis and provides good system documentation. However, the tool only weakly shows input and output detail. The data dictionary helps the analyst simplify the structure for meeting the data requirements of the system. If may be used at high or low levels of analysis, but it does not provide functional details, and it is not acceptable to many non-technical users. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 28. Structured English is best used when the problem requires sequences of actions with decisions. Decision trees are used to verify logic and in problems that invlove a few complex decisions resulting in a limited number of actions. 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. A decision table is perhaps the most useful tool for communicating problem to the user. Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]
- 29. Gagan Deep Rozy Computech Services 3rd Gate, K.U., Kurukshetra [email protected] Gagan Deep, RCS, 3rd Gate, K.U.K., [email protected]