Wednesday, 18 September 2013

Software

Software

Stages of a System Life Cycle

The system life cycle is a process of stages which occur during the development of a new IT system.

If organisations follow the stages of the system life cycle, they should be able to avoid many problems. 

The system life cycle consists of the following stages:

  1. Definition
  2. Investigation and analysis
  3. Design
  4. Implementation
  5. Testing
  6. Installation
  7. Documentation
  8. Evaluation
  9. Maintenance


Although all projects should start with the definition stage and end with the maintenance stage, the process is not always completely linear. After completion of one stage, it might be necessary to return to an earlier stage.

Importance of Defining a Problem Accurately
It is important to define a problem accurately because otherwise the problem could become miscalculated and the new system may not meet the customer's needs. Alternately, you could develop the correct system for the customer's needs, but overlook some of the major features and functions that were required. It also saves money if the problem is defined accurately. This means that because the problem was identified precisely, and developed accordingly, it saves time, money and man hours in the future correcting a problem which resulted from the original problem being misinterpreted.


Feasibility Studies
A feasibility study is generally what takes place next after the problem has been defined accurately. The function of a feasibility study is to determine whether it is actually possible or viable to go ahead with the proposed system being developed. The study takes into account factors such as cost, time and technical feasibility to develop. The purpose of this is to let you know whether the system is possible to develop with the budget you have, whether it is possible to do in a reasonable time scale and whether it is technically possible to create with the technology you have available to you.


Information Requirements of a System
It is important to determine the information requirements of a system so that you know what the system will need to be able to do during the development of the system. For example, if you designed a system without any knowledge of how big the memory needs to be or the amount of simultaneous work it needs to be able to do, then it is likely that the system developed does not have the right information requirements for what it is needed to do.


Different Methods of Fact Finding
  • Questionnaires - The first method of fact finding is in the form of questionnaires.The advantages of questionnaires are that they are set out in a standardized format, which means the information collected is presented in a clear and concise format because the information is generally collected in a Boolean format. Due to this, questionnaires are quite quick to fill out and they can be filled in by a large amount of people in one group. The disadvantages of questionnaires are that they are quite impersonal as all of the options within them tend to be Boolean. This means that the person filling out the questionnaire cannot provide any extra information, even if they have not understood one of the questions, meaning the information may be unreliable. Also, if the questionnaire is quite long, the person filling it out may answer the questions without really thinking if it is taking too long and they are bored.

  • Observation - The second method of fact finding is in the form of observation.The advantages of observation are that it takes less time to set up and interpret information than a method of fact finding in written format would. It is also less expensive as less materials are needed. They also provide more detail as you can see what is happening for yourself.The disadvantages of observation are that some information is not easy to interpret through sight, so some information may interpreted wrong and subsequently evaluated wrong because of this. It also may be difficult to use over a longer period of time.

  • Structured interviews - The third method of fact finding is in the form of structured interviews.The advantages of structured interviews are that due to the structuring of the interview, the subject remains on the main purpose of the interview, so there is little deviation. This means that the vast majority of information received is useful. They can also help to show the relationships between different concepts and provide detailed information on one subject.The disadvantages of structured interviews are that it may be difficult to direct the interview if the interviewer does not have a clear understanding of the concepts they are asking about. Some of the information may not be in the wanted depth that the interviewer is looking for.













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