System analysis and design


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  • Information systems are complex. To create new systems or modify existing ones, IS professionals go through several steps. Investigation is the process of understanding a problem or opportunity. IF we use building a new house as an analogy, this would be the period where you decide you need a new house & checkout your finances. Analysis is defining what the system should accomplish: what will its outputs and purpose be? Continuing the house analogy, here’s where you’d sit down with an architect & explain what kind of house you want, how many stories, how big, how many rooms of each kind you want, etc. The architect might draw sketches until you agree that he has the right idea. There wouldn’t be enough detail in the sketches to allow a house to be built from them. Design is determining how the system will accomplish it purpose. Design for the house would include developing the blueprints, heating and air conditioning specifications, electrical and plumbing specifications, and materials lists. Implementation involves creating the system and putting it into use. This would be when the house is built, landscaped, cleaned, and occupied. Maintenance involves monitoring and changing an information system throughout its life. This would be analogous to everything you do after you close on your house – for example, clean it, repair it, expand it, renovate it.
  • System analysis and design

    1. 1. System analysis and design
    2. 2. Information Systems Development <ul><li>Investigation </li></ul><ul><li>Analysis </li></ul><ul><li>Design </li></ul><ul><li>Implementation </li></ul><ul><li>Maintenance </li></ul>
    3. 3. <ul><li>The steps involved in system analysis are: </li></ul><ul><li>Fact finding </li></ul><ul><li>A feasibility study </li></ul><ul><li>Analysis phase </li></ul><ul><li>System design </li></ul><ul><li>Implementation </li></ul><ul><li>Testing </li></ul><ul><li>Documentation </li></ul><ul><li>evaluation </li></ul>
    4. 4. Fact finding <ul><li>It means that we need to find out how things are done at the moment </li></ul><ul><li>How can we do that? </li></ul>
    5. 5. Fact finding <ul><li>There are four main ways of finding out about existing systems these are : </li></ul><ul><li>Ask questions (interviewing people). </li></ul><ul><li>Getting people to fill in carefully designed questionnaires. </li></ul><ul><li>Sitting with various people to observe how the job is done at the moment </li></ul><ul><li>Inspecting any bits of paper ,screen displays and files which are used in the present system. </li></ul>
    6. 6. <ul><li>At the end of this procedures you should write down a report which describe the existing system with a description of the output needed from the new system . </li></ul><ul><li>Example……. </li></ul>
    7. 7. Feasibility study <ul><li>It looks at the chances of being able to solve a particular problem at a reasonable cost. </li></ul><ul><li>Feasibility report : it’s the document produced at the end of the study and will give an idea of the time the project is likely to take along some estimate of cost. </li></ul>
    8. 8. <ul><li>When the feasibility study ends? </li></ul><ul><li>It will end when a decision has been reached whether or not to proceed with the project . </li></ul>
    9. 9. Feasibility study <ul><li>technically feasible - is the new system technically possible to implement in the time available? </li></ul><ul><li>economically viable - will the cost of the new system be offset by savings once it is implemented? In other words, will it save the organisation money, time or allow them to perform more effectively? </li></ul>
    10. 10. <ul><li>the feasibility study includes: </li></ul><ul><li>A description of what the system is required to do (objective of the system) </li></ul><ul><li>A preliminary design so that the costs may be estimated </li></ul><ul><li>An alternative design so that the most suitable once can be chosen </li></ul><ul><li>A cost benefit analysis :this looks out the benefit and makes sure that they out weight the costs </li></ul><ul><li>The conclusion : decide whether its worth going a head with the project and which design has been chosen </li></ul>
    11. 11. The feasibility report <ul><li>It’s a summary of the results of the feasibility </li></ul><ul><li>It should include the following: </li></ul><ul><li>A brief description of the business and any problems with the existing one. </li></ul><ul><li>Details of what part of the business is being looked at </li></ul><ul><li>The objective of the proposed system </li></ul><ul><li>A list of some of the alternative solutions </li></ul>
    12. 12. The feasibility report <ul><li>The human technical and economic factors </li></ul><ul><li>ASK UR SELF HOW WE CAN GET THAT??? </li></ul>
    13. 13. <ul><li>Do the stuff have the expertise to cope with the new system </li></ul><ul><li>Is the technology available ..can it be done? </li></ul><ul><li>Is there enough money to go ahead? </li></ul>
    14. 14. Feasibility report <ul><li>A plan for the implementation </li></ul><ul><li>A proposed course of action (i.e. what the consultant /system analyst suggests the company should do next) </li></ul>
    15. 15. Analysis phase <ul><li>We use the feasibility study in this phase to design the new system </li></ul><ul><li>You should go in detail more than the feasibility study to find the weaknesses of the system . </li></ul><ul><li>In the analysis phase ,the charts (system flow charts and data flow diagrams) to help the analyst to understand the present system </li></ul>
    16. 16. Analysis phase <ul><li>The analysis phase includes : </li></ul><ul><li>Detailed objectives of the proposed system </li></ul><ul><li>Facts about the parts of the old system being replaced by the new system </li></ul><ul><li>Any constraints on the system </li></ul><ul><li>An update of the cost /benefit analysis based on the new information </li></ul>
    17. 17. <ul><li>5.An update of the plan for further development of the system </li></ul><ul><li>This will include the responsibilities of the members of the team involved with the project and deadlines by which the stage must be completed </li></ul>