The System Life Cycle

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What are the 5 stages of the system life cycle?
1) Analysis 2) Design 3) Implementation 4) Documentation 5) Evaluation
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What happens in the analysis stage?
The current system is looked at in detail and the problems with it are identified.
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Why is the analysis stage important?
It collects the information that allows the analysis to take place.
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What are the methods for analysis?
Interview, Observation, Questionnaires, Using existing documentation
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Give two advantages of interviews.
1) Questions can be explained if the interviewee doesn't fully understand them. 2) Questions can be made more specific as it's one to one.
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Give two disadvantages of interviews.
1) Time consuming if you have to interview numerous people 2) Expensive.
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Give two advantages of observations.
1) Specific or important details can be recorded. 2) Cheap
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Give two disadvantages of observations.
1) If observation is in time periods, some important things could happen in the time when there isn't anyone observing 2) Can get boring.
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Give two advantages of questionnaires.
1) Easy to hand out to a wide range of people. 2) They can be presented in many different formats such as in emails, flyers, specific documents, etc.
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Give two disadvantages of questionnaires.
1) Questions are very general therefore specific answers cannot be found 2) Many people might not respond to the questionnaire, therefore it could be very time-consuming.
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Give two advantages of using existing documentation.
1) A thorough, detailed description of the current system is obtained 2) It allows the analyst to get an idea of the scale of the problem
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Give two disadvantages of using existing documentation.
1) It can be very time-consuming to read through all the paperwork 2) Because of the analyst's time, it is relatively expensive.
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What happens in the design stage?
The solution to the problems are identified from the analysis.
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Give 7 tasks that have to be completed in the design stage.
Designing data capture forms/input forms, designing system flowcharts and pseudo code, designing a testing strategy/plan, designing the file structures, designing validation and verification rules, designing hardware and software requirements
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What is pseudo code?
A notation resembling a simplified programming language used in program design.
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Give two verification methods.
Double entry and visual check.
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What is double entry?
The data is entered twice using two different people. The computer compares the two entries and identifies any differences.
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What is visual check?
The checking for errors by comparing entered data on the screen with the data in the original document.
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Give 8 validation checks.
Range check, length check, character/type check, format/picture check, limit check, presence check, consistency check, check digit.
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What is range check?
It checks whether data is within given/acceptable values.
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What is length check?
It checks if the input data contains the required number of characters.
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What is character/type check?
It checks that the input data does not contain invalid characters.
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What is format/picture check?
It checks that the data is in a specific format.
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What is limit check?
It is similar to the rage check, except that only one of the limits is checked.
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What is presence check?
It checks if data is actually present and has not been missed out.
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What is consistency check?
It checks if fields correspond with each other.
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What is check digit?
It looks at an extra digit which is calculated from the digits of a number and then put on the end of the number.
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What 3 types of error can check digits identify?
1) If two digits have been inverted during the input. 2) If an incorrect digit is entered twice. 3) If a digit is missed out altogether.
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What is a system flowchart?
A diagram of the flow of data or the sequence of steps needed to complete a process.
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What are the 4 types of test data?
Normal test data, Live data, Extreme data and Abnormal data.
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What is normal test data?
The data generated by the system's analyst that follows the expected formats and types, and produces outcomes for which the system has been designed.
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What is live data?
The testing with actual data within the current system. It tests all eventualities that employees encounter in their daily use of the system.
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What is abnormal test data?
Is used to ensure that the system rejects certain data entries that fall beyond or below the given boundaries.
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What is extreme test data?
The data values that are at the extremes of acceptable, or at the boundaries. They are perfectly valid, but generally rare.
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Give 3 purposes of test data.
1) Ensures that inputs to the system are valid. 2) Ensures that outputs from the system are accurate. 3) Ensures that outputs are presented clearly
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What are the two main areas for testing?
The data entry testing and the user interface testing.
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What should be considered in user interface testing?
Input devices, output devices and general issues such as that displays are easy to read or any messages are clear to users.
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What are the 4 different methods of implementation?
Direct Changeover, Parallel Running, Pilot Implementation, Phased implementation
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What is direct changeover?
The old system is stopped overnight and the new system introduced immediately.
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Give 3 advantages of direct changeover.
1) Benefits are immediate. 2) Costs are reduced since only one system is used. 3) There is less likelihood of a malfunction since the new system will have been fully tested.
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Give 2 disadvantages of direct changeover?
1) Consequences can be disastrous if the new system fails. 2) Staff doesn't have time to get accustomed.
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What is parallel running?
The old and new systems are run side by side for a time before the new system takes over altogether.
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Give 3 advantages of parallel running?
1) If the new system fails, the old system is still available as a back-up. 2) It's possible to train staff gradually. 3) Staff have time to get used to the new system.
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Give a disadvantage of parallel running.
It's more expensive than direct changeover, since extra staff are needed to run both systems together.
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What is pilot implementation?
The new system is introduced into one part of the company and its performance assessed.
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Give 3 advantages of pilot implementation?
1) If the new system fails, only one part of the company is affected. 2) It's possible to train staff in one area only - faster and less costly than parallel. 3) Costs are less than in parallel running - only one part of the system is being used.
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Give a disadvantage of pilot implementation.
It's more expensive than direct changeover, since each pilot scheme needs to be evaluated before the next stage is introduced.
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What is phased implementation?
Initially, only part of the new system is introduced. Only when it proves to work satisfactorily is the next part introduced, and so on, until the old system is fully replaced.
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Give 2 advantages of phased implementation.
1) If the latest part fails, it is only necessary to go back in the system to the point of failure, hence failure is not disastrous. 2) It's possible to ensure the system works properly before expanding.
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Give a disadvantage of phased implementation.
It's more expensive than direct changeover, since it is necessary to evaluate each phase before moving to the next stage.
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What 2 types of documentation are there?
User and technical documentation.
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What is user documentation for?
It's designed to help users to learn how to used the software or system.
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Give 7 examples of what is included in user documentation.
1) Instructions on how to perform basic tasks. 2) Screen layouts 3) Print layouts 4) Hardware and software requirements 5) Sample runs with test data and results 6) Error handling 7) Troubleshooting guide
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What is technical documentation?
It's designed to help programmers and analysts who need to make improvements to the system or repair/maintain the system.
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Give 10 examples of what is included in technical documentation.
1) Program listing/coding 2) Flowcharts/algorithms 3) Memory requirements 4) Hardware and software requirements 5) Known bugs in the system 6) Variables used 7) File structures 8) Sample runs 9) Output formats 10) Validation rules
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Why is evaluation important?
Organisations need to establish how well the new system works in order to be able to report to the system's analyst. They want to know if the new system is an efficient and appropriate solution to the earlier identified problems.
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Give 4 examples of what an analyst will to to evaluate a system.
1) Identify any limitations in the system 2) Compare the final solution with the original requirement. 3) Observing users perform set tasks, comparing old with new. 4) Compare test results and performances of the new system to the old one.
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Why might hardware need to be updated?
1) Feedback from end users 2) New hardware comes on the market, making change necessary. 3) There are changes within the company which require new devices to be added or updated.
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Why might software need to be updated?
1) Feedback from users. 2) Changes to the company structure or how the company works may need modifications to the software. 3) changes in legislation may need modifications to the software.s
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Card 4

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Card 5

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Give two advantages of interviews.

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