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System Development - Computer Studies Form 3

Objectives

By the end of the topic, the learner should be able to:

  • Describe a system
  • Define an information system
  • State the purpose of an information system
  • Identify the stages of systems development
  • Develop a system using a case study
  • Write a report on the case study

  • Definition of a system.

    A system is a set of organized independent components that work together within a given boundary to achieve a common goal. 


     

    Components of a system

    Move the mouse over the blocks to view details.

     

    Purpose of System Development

     

    There must be a reason for the development of a system. This may come either from the management, users, customers, government or any stakeholders of the organization. Some of the purposes for developing a new system may include;

     

    -High failure rate of the existing system -   The current system maybe failing very often causing the organization to look for a better system.

     

    -Slow in processing - The current system maybe slow in processing data.

     

    - Complaints from users -   The current system may fail to meet users' expectations.

     

    -Decline in profits - The current system may cause a lot of loss in terms of costs or time.

     

    -Errors in the system -   The system may have many errors and there may be a need to come up with an error-free system.

     


    -High cost of maintenance -   The cost of maintaining the current system maybe rising tremendously and as a result there might be a need to reduce the cost through a new system.

     

    -Lack of security -   The current system may lack adequate security controls and this may call for the development of a more secure system.

     

    -The new government policies -   New government policies may cause an organization to change their system in order to comply with the new directives and standards.

     

    -Technological advancement -   Rapid changes in technology may cause an organization to change their system to adapt to the new technologies.

     

    -Stiff competition for quality products/services delivery -   Stiff competition for the same market and same services/products by different providers may cause an organization to look into better ways of maintaining a competitive edge over the others by developing a new system.

     

     

    Conceptual and Physical Systems

    Systems can be conceptual (abstract) or physical. An abstract system is an orderly arrangement of independent ideas.

    Conceptual systems are concerned with theoretical structures which may or may not have counterpart in the real world. Thus conceptual systems are systems of explanation or ideas or constructs, for example, data flow diagrams in system development.
     

    Physical systems are concrete operational systems made up of people, material, machines energy and other physical things. Physical systems can display activity or behaviour. Examples include business organizations and computer systems.


    Information Systems

    Definition of an Information system.

     

    An information system can be defined as a system that accepts data resources as input and processes them into information products as output.

     

    Information systems can also be defined as an arrangement of people, data, processes, communication and information technology that interact to support and improve day-to-day operations as well as support the problem-solving and decision making needs of an organization.


    Components of an Information system

     

    End users - End users are people who enter input into the system and use the output from the system. Examples of end users include: students, accountants, teachers, salespersons and engineers.

     

    ,

    1. Information System Specialists -   These are people who develop and operate information systems. They include systems analysts, programmers and computer operators. Systems analysts design information systems based on the information requirements of end users, programmers prepare computer programs based on the specifications of systems analysts, and computer operators operate large computer systems.

     



    2. Hardware - ;Hardware refers to all physical devices and materials used in information processing. Hardware includes machines such as computers, output devices, input devices, communication media, storage devices and media.



    3.  Software-The term software is generally used to refer to programs, which direct and control computer hardware as well as procedures. Procedures refer to the sets of information processing instructions needed by people.  Software also includes: communication software e.g. networking software, application software among others.



    4. Data -   Data is can be defined as raw facts and Figures that have less meaning to the user. For example in a school systems data that may be stored about a student include: Age, Name, admission number, Class, stream, date of birth, date of admission.

     


    Classification by Mode of Processing


    (b) Online Systems
    This is a type of information system where the transactions are captured by the online data entry devices.


    (c) Real time Systems
    This is a type of information system where data capture as well as their processing is carried out at the same time as the transaction is taking place. The records files are updated instantly.

     

    Examples of real time systems include:
    -Airline reservation system
    - Hotel reservation system
    -Industrial Process Control Systems

    Classification by System Objectives

    (a) Transaction Processing Systems (TPS)


    These are information systems that capture and process data about business transactions. Their objective is to process transactions in order to update records and generate reports.Examples include:


    -Payroll systems -Electricity billing systems -Stock control systems -Airline reservation systems
    (b) Decision Support Systems (DSS)
    These are information systems that provide the users with decision oriented information whenever a decision-making situation arises. Their objective is to support managerial decisions and is usually based on a model of decision making domain.

     

    Examples include spreadsheet programs such as Microsoft Excel and
    Lotus 1-2-3

    Make changes in any of the following columns; stock sold, buying price, selling price and observe how the changes affect total buying price, total selling price, profit/loss as well as remarks.


    (c) Expert Systems (ES)
    These are programmed decision making information systems that capture and reproduce the knowledge and expertise of an expert problem solver or decision maker and then simulates the 'thinking' or 'actions' of that expert. They initiate the reasoning and the logic of a human expert in a given field such as the medical field, banking and legal field.


    (d) Management Information Systems (MIS)
    These are information systems that condense and convert Transaction Processing Systems' data into information for monitoring performance and managing organizations. They provide management oriented reports which are usually generated on a predetermined schedule and appear in a prearranged format.
     

    Examples of such reports include:
    -Trading Profit and Loss Accounts
    -Income and Expenditure Accounts
    -Bank Statements.



    Information system

    Information Systems can be classified in many ways such as on:
    -The basis of the mode of processing
     - The system objectives
    -The type of function the system supports

     

     

    Lesson objectives


    By the end of the lesson the learner should be able to:


    1.   State the purpose of an information system.

     



     

    By the end of the lesson the learner should be able to:


    1.  Define system development
    2. State the purpose of system development
    3. Define system development methodology

     

    Lesson objectives


    By the end of the lesson the learner should be able to:


    1. Define System Development Life Cycle (SDLC)
    2. State the stages of System Development Life Cycle

     

    Systems Development Life Cycle (SDLC)

     

    It consists of the following stages:

    Problem recognition and definition

    Information gathering

    Requirements specifications

     

    System design

    System construction (coding)

    System implementation and testing

    System review and maintenance



    Stages of System Development Life Cycle (SDLC)

     

    SDLC recognizes the existence of a life cycle of a system from the conception of an idea to the decay of the system. Stages of System Development Life Cycle (SDLC)The eight stages of SDLC include:

     

    1. Problem Identification

    2. Feasibility study

    3. System requirements analysis

    4. System design

    5. System coding 6. System testing 7. System implementation

    8. System evaluation and maintenance

     

    Let us briefly look at the activities of each phase.

     

    Problem Identification Stage

    In problem recognition stage, a problem is identified and its magnitude expressed. It is important to be very keen in this stage as each detail affects the next stages.
    In the Problem definition stage, the problem is interpreted so that it can be well understood.  In this stage the objectives of the new system are set and its scope (boundary) determined. The purposes of the problem definition stage include:
         -It helps in pinpointing the problems
    -It helps in setting proper system goals
    The main output at this stage is the Problem Statement.

    The last step in this stage is to carry out a feasibility study.

     

    Lesson objectives


    By the end of the lesson the learner should be able to:


    1.   State the purpose of feasibility stage in system development


    2. Identify the various methods of carrying out feasibility studies.

     

    Feasibility study

     

    Feasibility study is carried out whenever there is a complex problem or opportunity. Feasibility study is a study carried out to determine the possibility of either improving the existing system or developing a completely new system. This study helps to obtain an overview of the problem and rough assessment of whether feasible solutions exist. This is important to avoid committing large resources to a project that fails at a later stage.

     

    The feasibility study is needed to:

     

    1. Answer the question as to whether a new system is necessary or not.

    2. Determine the potential of the existing system

    3. Know what should be included in the new system

    4. Define the problems and objectives of the new system

    5. Avoid incurring unnecessary costs at a later stage when the system has been implemented

    6. Avoid rushed implementation of the new system.

     

    Methods of Carrying out a Feasibility Study The following are methods used to carry out a feasibility study:

     

    1. Technical Feasibility
    2. Economic Feasibility
    3. Operational Feasibility
    4. Schedule Feasibility
    5. Legal Feasibility

     

    The main output of this stage is a Feasibility Report.

     

    You can review the methods used to carry out a feasibility study by pointing on the desired method.


    Lesson objectives


    By the end of the lesson the learner should be able to:


    1. Define the term system requirements
    2. State the purpose of system requirements
    3. List various ways of assessing the system requirements

     

    SYSTEM REQUIREMENTS SPECIFICATION

    In this stage the system analyst identifies what is needed from and for the new system in order for it to achieve its defined objectives.

     

    Some of the requirement specifications considered include:

     

  • Output Requirements -What outputs are needed
  • Input Requirements -What inputs are needed to obtain these outputs
  • Processing Requirements - What operations the new system must perform to obtain these outputs
  • Hardware/Software Requirements - What hardware and software resources must be used
  • Control Requirements - What operational controls are needed
  • Storage requirements - what data stores are going to be used for storage of data

  •  

    INFORMATION GATHERING

     

    It refers to different ways used to collect data. Methods of data collection refer to the ideal strategy or tool or approach to use to collect or gather data. Some of the methods that can be used include:

  • Questionnaires
  • Interviews
  • Observation
  • Documentation review

  •  

    System design

     

    This is a stage where the analyst uses a suitable algorithm to depict a systems logic. The tools commonly used are system flowchart and data flow diagrams.

     

    The system is then defined in terms of its specifications which include -Report/Output designs: The output design is either the printed report or format that is displayed on the computer screen. It should be based on the user requirements.


    Input Form Design


    An input form is a form used for entering new records or modifying records in a file or database.

     


    -Data Flow Diagrams

     

    The DFD is a diagram that shows how the data manipulated by a system flows through the various processes.


    -System Flowchart
    This is a diagram showing an overview of the processing in a complete system. They are a well-established method of showing:


    -inputs to a particular part of the system
    -what actions are taken to process the data
    -What moves out of this part to somewhere else?


    The basic system flowchart symbols are as shown below;

     

     

    The next diagram is a sample system flowchart for a payroll system.

     


    -Table/File designs


    A table is a set of data elements that is organized using a model of:
    -vertical columns
    -horizontal rows

     

    A table has a specified number of columns, but can have any number of rows. Each row is identified by the values appearing in a particular column subset which has been identified as a candidate key.


    The output of this phase will consist of the specifications that must describe both what the new system will do and how it will work. The output is Specifications of the new system.


     

    System Coding (Construction)

    This refers to the act of building an information system based on the design specifications.


      An organization can outsource programmers or use their own programmers to develop the system. The system analyst and the programmers choose a suitable programming language for the problem specified. Once the software has been developed, the hardware to run it must be acquired or upgraded.  The outputs of this phase are the programs and their documentations and the user manuals.

     

    Also under this stage, system testing occurs.

    .

    System testing

     

    This is the running of the whole system against test data to evaluate the compliance of of the systems requirements with the resources which include:
    -Hardware devices -Computer programs -Information-processing procedures

    Programs are tested with an attempt to simulate all conditions that may arise during processing.For quality programming, programs are structured to have modules to assist the development, testing and maintenance of a system. Program testing usually proceeds from higher to lower levels of program modules until the entire program is tested as a unit. The program is then tested along with other related programs in a final systems test.


    System testing


    System testing is done in three basic stages;

     

    Unit testing; This is the testing of individual parts of the system. If the system is written as a collaborative effort by many programmers, each part of the system is tested separately as a unit (program module).

     

    System testing; This is where program modules are linked together and test data is used to see if the parts work together. At this point, actual data organization may be used to test the system.

     

    User acceptance testing; This is done to ensure the system meets the users' needs. It is usually carried out by the user or on behalf of the users.

     

    Types of Test Data

    -Live data;This is data that is currently being used by the organization.

    -Program data;This is data used by the programmer when developing the program

    -Historical data;This is data which was previously used by the organization and which is no longer valid.

    -Suite data;This is data for the whole system to ensure that the suite works correctly and that various program links work as required.


    It's important when testing to produce tentative copies of displays, reports, and other output. These should be reviewed by end users of the proposed systems for possible design errors.


    Testing should not occur only during the system's testing phase, but throughout the system's development process. For example, Input documents, Screen displays, processing procedures are examined and critiqued by the development team during the systems design phase. The outputs of this phase are test results and a working system ready to be delivered to the users.

     

     

    System Implementation

     

    It is the installation and configuration of the new system to that it can be used.
    Activities performed during this stage include;

    • Installation of hardware and software  which include:
    • File conversion
    • Training users

    Implementation Strategies

    There are 3 major ways of implementing a new system, namely:

  • Straight (direct) changeover - this a changeover strategy where the old system is abandoned and the new system is put to use immediately
  • Parallel changeover -this is a changeover strategy where the old and the new system are used concurrently. When the users feel comfortable with the new system, the old system is phased out.
  • Phase changeover -this is where each part/module of the new system is implemented in stages.
  • Pilot changeover- this is where the new system is implemented in only one department/branch of the organization. If successful, it is implemented in all the other departments/branches
  •  


    Site preparation

    Site preparation and installation of hardware and software which include:
    Acquiring new buildings
    Wiring
    air-conditioning systems
    Security systems


    Direct conversion

    This is where the old system is completely and immediately replaced by the new system. This is usually adapted when the two systems are fundamentally different hence no need to run them together.

     

    Advantage of this approach is:


    It is less expensive since there is no need for maintaining two systems.

    Disadvantage of this approach is:
    If the new system fails, the organization may become totally grounded.

    Parallel conversion

     

    This is where the old and the new system are operated until the system development team, end users and management agree to switch completely over to the new system.

    Advantages of this approach are:


    The operations and results of both systems are compared and evaluated.
    Errors can be identified and corrected and the operating problems can be solved before the old system is abandoned.

    Disadvantage of this approach is:


    It is expensive to maintain two systems, as you may need to employ more people to cope up with the task of using two systems

     

    Phased conversion

    This is where only few departments, branch offices, or plant locations at a time implement the new system. A phased conversion allows a gradual implementation process to take place within an organization.
    Pilot conversion
    This is where one department or other work site serves as a test site. A new system can be tried out at this site until developers feel it can be implemented throughout the organization.

     

    Lesson objectives


    By the end of the lesson the learner should be able to:
    1.  Define the term system evaluation
    2.  Define the term system maintenance
    3.  State the importance of system maintenance
    4.  State the importance of system evaluation

     

    Introduction

     

    System development is the process of defining, designing, testing and implementing a new software or program. System development is the creation of a system using a step by step procedure.

    Background

    In Form One you learned about a computer system and how computer hardware, computer software and computer users (live ware) all interact as a unit to accomplish the task of data processing.  In Form Three you learned about:
     

     

    - Data processing where you had an insight into the fundamental data processing concepts, methods and modes   -Elementary Programming Principles where you were introduced to programming concepts, languages and stages of program development.

     

    All the above provide a base for this topic; System Development that introduces you to developing information systems which are the power behind data processing.


















     

    Hello students; Welcome to Form 3 computer lessons. In this topic we shall cover the following areas:
    (a) Description of a system
    (b) Definition of an information system
    (c) Purpose of an information system
    (d) Stages of system development


    Open and Closed Systems:

     

    An open system is one that interacts with the environment. A business organization is an open system because it exchanges material and information with the environment. It does not provide for its own control or modification thus it does not supervise itself. It needs to be supervised by people e.g. the school system. Some of the internal components include: students, staff, and non-teaching staff e.t.c.  Some of the external components include parents and suppliers. Both the internal and external components work together to ensure that the teaching and learning process is successful.


    Another example in the banking sector, Automatic Teller Machines (ATM) must be feed with money from within the bank so that the customers can withdraw the money through the ATM. Some banks give a provision of depositing money by customer through the ATMs. These operations regulate the performance of system.


    A closed system is a system which has its own well defined inputs and outputs but is not subjected to disturbances from the environment (outside the system). This is a system which is self-contained. It is independent of environmental influences. It does not exchange material and information with its environment. Closed systems are very rare and if they exist they will finally run down or become disorganized.

     

    Please give an example


    Hard and Soft Systems
    Systems can also be classified as hard or soft systems.
    A soft system is a system that has got no clearly defined goals and objectives hence its performance cannot be precisely measured.


    For example, sales tracking system where sales performance depend on human factors such the prevailing conditions (availability of money, customers, products) and human preferences.
    Hard system is a system whose goals and objectives are clearly defined and the outcomes from the processes can be precisely measured.


    For example, in a stock control system, it is possible to know exactly the stock levels, the reorder and profits can be accurately predicted if all the stock is sold.


    Deterministic and Probabilistic Systems


    Systems can also be deterministic or probabilistic. A deterministic system operates in a predictable manner. If one knows the state of a system at a given point of time or can predict the next state without error then it is a deterministic system.

     

    If one cannot predict the next state without an error then it is a probabilistic system.

    For example, in computer systems the outputs are deterministic while weather forecasting systems and inventory systems are probabilistic.

     

    PURPOSE OF AN INFORMATION SYSTEM

     

    Information Systems play major roles in organizations which lead to improvement in efficiency and effectiveness of business processes.There are many reasons why businesses should want to develop information systems but some of the most common reasons are:


    -To reduce manpower costs;The introduction of computer-based systems has often enabled work to be done by fewer staff or has permitted new tasks to be undertaken without increasing staffing levels.


    -To improve customer service; Computer systems can often allow organizations to serve customers more quickly or to provide them with additional services.


    -To improve management of information; Management decisions can only be as good as the information on which they are based on. Many computer systems have been designed to produce correct, accurate, relevant and timely information.

     

    -To secure or defend advantage over potential competitors; This is becoming a major justification for spending on information systems.

     

    Purpose of System Development


    There must be a reason for the development of a system. This may come either from the management, users, customers, government or any stakeholders of the organization. Some of the purposes for developing a new system may include: High failure rate of the existing system


    The current system maybe failing very often causing the organization to look for a better system.

    -Slow in processing; The current system maybe slow in processing data.

    - Complaints from users; The current system may fail to meet users' expectations.

    -Decline in profits; The current system may cause a lot of loss in terms of costs or time.

    -Errors in the system; The system may have many errors and there may be a need to come up with an error-free system.

     

    -High cost of maintenance; The cost of maintaining the current system maybe rising tremendously and as a result there might be a need to reduce the cost through a new system.

    -Lack of security; The current system may lack adequate security controls and this may call for the development of a more secure system.

    -The new government policies
    New government policies may cause an organization to change their system in order to comply with the new directives and standards.

     

    -Technological advancement
    Rapid changes in technology may cause an organization to change their system to adapt to the new technologies.

    -tiff competition for quality products/services delivery
    Stiff competition for the same market and same services/products by different providers may cause an organization to look into better ways of maintaining a competitive edge over the others by developing a new system.


    For proper understanding of the problem identification we will use the following case study.
     XYZ insurance firm deals with payments of clients claims. It has eight employees in total, two field officers, two supervisors, three clerks and one manager serving about one hundred clients. The office space is 15 feet squared partitioned by block boards to accommodate two other offices; one for a manager and other for two supervisors. The remaining space is used by the three clerks. One long table serves the clerks and a big cabinet for storage of files can be seen at the corner. The customers complain of late claims payments, errors in their claims and a lot of time spent waiting to be served. The employees complain of the small and congested office.

     

    Mr. Jero a system analyst has been contracted to work on the system with a view of coming up with a better alternative system. He has identified the problem as lack of adequate office space and few workers with a lot of workload.


    Let us analyze the problem in the case study above and try to find out whether Mr. Jero has correctly identified the problem.

    Mr. Jero has not correctly identified the problems affecting the operations of XYZ Company. He may have misinterpreted the problem because he may not have taken considerable time and consulted all the stake holders.


    Let us critically analyze the problem:


    What is the actual problem? XYZ use a manual system for their operations. This system has the following drawbacks;Inaccuracy Slow access to records stored in manual file folders Poor storage facilities Slow in processing

    [Insert a picture of people working in an office using the manual system. Include in the picture a file cabinet and file folders piled up on the tables]

    What are the causes of this problem?

     

    The problem of inaccuracy may have been caused by transcription errors, misreading errors, updating a record in one file folder and failing to update a related record in another file folder.

     

    Is it important to solve this problem?

    It is important to solve the problem because failure to change to a better and efficient system can easily bring down the firm. Poor service delivery to the customers may lead to losing them to the potential competitors.

    What are the likely solutions to the problem?

    Change to a computerized system that will address the problems identified.

    The system analyst can identify the problem verbally getting message from the end users such as the clients and the clerks. Problems may also be submitted on a written form called Problem Report Form. The systems analyst may also sense certain problem signals while analyzing a particular problem.
    The advantages of the problem definition stage include:

    • It helps in pinpointing the problems
    • It helps in setting proper system goals

    Before any further steps can be taken up, the problem must be stated in clear and unambiguous words.

    The main output at this stage is the Problem Statement.


    Technical Feasibility

    Technical feasibility study is done to assess whether the development of the new system can be done with the:

  • present equipment
  • current procedures
  • existing software
  • existing technology
  • available personnel
  •  

      If new technology is needed alternatives that will lead the work to completion must be considered.

     

    Economic Feasibility

     

    Economic feasibility study is carried out to determine the development costs and expected savings from the new system. The costs must include both initial costs and recurring costs.

     

    Initial costs may include:  

    -Feasibility study costs  

    -The costs for converting from current system to new system  

    -Construction or remodeling of computer rooms/facilities  

    -Costs for buying hardware and software for the new system  

    -Costs for training the staff how to use the new system

     

    Recurring costs may include:  

    -Salaries for personnel  

    -Equipment maintenance

     

    Operational Feasibility

     

    This is a study done to determine whether the users would be able to operate the new system or they will require training. The new system should fit well into the existing operational structure of the organization.

     

    Schedule Feasibility

     

    This is a study carried out to determine the time duration required to design and implement the system. Depending on the complexity of the project, it may take a few months for a simple system or even years for more complex systems to be completed.


    Legal Feasibility

    This is a study carried out to check whether the new system is in line with the current laws. The new system is evaluated to ensure it complies with the company objectives and the government policy.


    Review of the current document

    This is the studying of the available documents that portrays the nature of the existing system. These are documents such as reports, forms, manuals, business plans, policy statements, organizational charts etc. These documents are a good place to start because they at least tell you how things are and how they are supposed to be. They provide leads on people and areas to pursue for further information.

     

    Interviews

    An interview is whereby the interviewer probes the user of the current system in order to get information about the current system.  They are face-to-face encounters

    Advantaged of interviews among others include:
      - They provide in-depth data which is not possible to get using a questionnaire
      - They make it possible to obtain data require to meet specific objectives
      - They guard against confusing the questions since the interviewer can clarify the questions thereby helping the respondent give relevant responses. - They are more flexible than questionnaires because the interviewer can adapt to the situation. Interviewer can get more information by using probing questions unlike questionnaires

    Questionnaires

    A questionnaire is a document containing a number of questions set by the systems analyst used to gather information from users about the current system.


    Advantages of Questionnaires include: 1. Questionnaires provide a relatively inexpensive means of gathering data from a large number of people. 2. Responses can be tabulated and analyzed quickly.
    Disadvantages of Questionnaires include: 1. The number of respondents is often low. 2. There is no guarantee that a respondent will answer all the questions.

     

    Observation

     

    This is a fact-finding method where the systems analyst either participates in or watches a person perform activities to learn about to learn about the system.


    Advantages of Observation include:


    1. Observation is relatively inexpensive compared with other fact-finding methods.
    2. The systems analyst is able to see exactly what is being done. Through observation the systems analyst can identify tasks that have been missed or inaccurately described by other fact-finding methods.

     

    Disadvantages of Observation include:

    1. Because people usually feel uncomfortable when being watched, they may unwillingly perform differently when being observed.


    2. The work being observed may at times not involve the level of difficulty or volume normally experienced. Requirement analysis is one of the most important phases of the system development (SDLC). This stage should yield a requirement statement specifying enough details about the new system requirements.

     


    Documentation

    It is the writing of detailed instructions at every stage of the system development. This instructions can be used to guide the programmers, users and for future maintenance of the system


    We have different types of documentations:

  • User oriented documentation
  • Operator oriented documentation
  • Programmer oriented documentation
  • Good system documentation usually consists of the following:

  • Reports on fact finding/information gathering
  • System flowchart
  • Table/file structure/descriptions
  • Sample data
  • Output reports
  • User manual
  • Training of users

     

    This is the teaching of the end users through the following training tools to operate the new system.
    -Instruction manuals
    -Videotapes
    -Live classes
    -One-on-one,
    -Side-by-side
    -Teacher-student training

     

    File conversion

    This involves converting the existing files into a form suitable/compatible with the newly developed system.

    System change-over (System Conversion)

     

    This is usually a conversion process in which the personnel, procedures, equipment, input/output forms, and database of an old information system must be converted to the requirements of a new system. Four major forms of system conversion include:

     


    Direct conversion
    This is where the old system is completely and immediately replaced by the new system. This is usually adapted when the two systems are fundamentally different hence no need to run them together.

    Advantage of this approach is: -It is less expensive since there is no need for maintaining two systems.

    Disadvantage of this approach is: -If the new system fails, the organization may become totally grounded.


    Parallel conversion
    This is where the old and the new system are operated until the system development team, end users and management agree to switch completely over to the new system.

    Advantages of this approach are:
    -The operations and results of both systems are compared and evaluated.
    -Errors can be identified and corrected and the operating problems can be solved before the old system is abandoned.

     

    Disadvantage of this approach is:
    -It is expensive to maintain two systems, as you may need to employ more people to cope up with the task of using two systems


    Phased conversion
    This is where only few departments, branch offices, or plant locations at a time implement the new system. A phased conversion allows a gradual implementation process to take place within an organization.
     

    Pilot conversion


    This is where one department or other work site serves as a test site. A new system can be tried out at this site until developers feel it can be implemented throughout the organization.

     

    SYSTEM REVIEW AND MAINTENANCE

     

    System review involves assessing the strengths and weaknesses of information systems in order to improve their effectiveness.
    Personnel who operate and use the system will make mistakes simply because they are not familiar with it. Such errors usually diminish as experience is gained with a new system.
    System maintenance is making modifications to a system due to changes in the business organization or the business environment.

     

    This could be as a result of:

  • Change in user requirements
  • New business ventures
  • New tax legislation
  • The maintenance process must correct errors in the development or use of a system. It includes a periodic review or audit of a system to ensure that it is operating properly and meeting its objectives.

     

    Types of System Maintenance

    There are three types of system maintenance:
    1. Corrective maintenance
    This is done to correct error in the system or when the system fails.


    2. Perfective maintenance
    This is done in order to improve the system and add new functional system requirements.
    3. Adaptive maintenance
    This involves changing the system so that it can operate in a different environment.

    Definition of System Development: :

    System development is the process of defining, designing, testing and implementing a new software application or program.


    Systems Development Methods:

     

    These refer to the different ways that can be used to develop a system. Some of these methods include: waterfall method, prototyping method, evolutionary method and System Development Lifecycle (SDLC).For this lesson we will adapt the Systems Development Life Cycle (SDLC) method.


    1. Systems Development Life Cycle (SDLC)

    2. Waterfall Model



    3. Prototyping
    The Prototyping Model is a systems development method in which a prototype (an early approximation of a final system or product) is built, tested, and then reworked as necessary until an acceptable prototype is finally achieved from which the complete system or product can now be developed.

    For our curriculum we will adapt the Systems Development Life Cycle (SDLC).


    System evaluation :

    System evaluation involves assessing the strengths and weaknesses of information systems in order to improve their effectiveness.

    Personnel who operate and use the system will make mistakes simply because they are not familiar with it. Such errors usually diminish as experience is gained with a new system. System maintenance involves making modifications to a system due to changes in the business organization or the business environment. This could be as a result of: -Change in user requirements
    -new business ventures
    -new tax legislation

    The maintenance process must correct errors in the development or use of a system. It includes a periodic review or audit of a system to ensure that it is operating properly and meeting its objectives.


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