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The Main Stages of the Systems Cycle - 5.3.3


Revision Points: (Full course)
Candidates are expected to be able to:
  • identify the main stages of the systems cycle: investigation and analysis, design, development and testing of a working system, implementation, monitoring, maintenance;

As a business develops it will often want to introduce a new computerised system to solve one or more problems that it has with its existing computerised or non-computerised system.

The system cycle is the process by which an existing system is replaced with another system.

There are a number of stages in the systems cycle that should be followed to be sure that the new system solves the problems of the system it replaces.

Investigation and Analysis:

During this stage a business will employ a systems analyst to investigate the existing system in depth to see:

  • what the problems are with the existing system;
  • if a new system would be cost effective (would the savings made due to increased efficiency etc. be greater than the cost of the hardware purchases, software development and staff training involved);
  • is a new system technically possible in terms of the hardware and software required to solve the problems with the existing system.

This is often known as a feasibility study.

The investigation part of this stage involves a study of the inputs, processing and outputs of the existing system.  This could be done using a range of techniques including:

  • questionnaires;
  • interviewing staff;
  • direct observation;
  • a study of existing documentation such as data capture forms and printed outputs.

The analysis part of this stage involves breaking down the problems with the existing system and looking at alternative ways of solving them.  These will range from:

  • keeping the existing system because any changes are unfeasible due to cost and/or technical reasons;
  • keeping the parts of the existing system that work well and only developing those parts that do not work well;
  • using an 'off the shelf' solution and changing the way the business works to fit in with it;
  • using an 'off the shelf' solution and then adapting it to fit with the way the business already works;
  • developing an customised (bespoke) solution to fit with the way the business already works.

Design:

During this stage any or all of the following might have to be designed:

  • data capture forms (on-screen and printed);
  • output formats (on-screen and printed);
  • data file structures;
  • hardware specifications (including computer, printer, networking specifications etc.);
  • software specifications;
  • test plans;
  • plans for how to export data from the old system and import it into the new system.

Development & Testing:

During this phase the software and hardware engineers work together to develop a working system, following the designs from the previous stage.

Each phase is tested as it is developed.  Once all the development has taken place the whole system will be tested using the test plan devised in the design stage.  If any test results are not satisfactory then changes will be made and the system tested again.

The user documentation will also be developed at this stage to help train staff to use the new system. Such user documentation would typically include:

  • installation instructions;
  • instructions on how to input data, process it and output information using the new system;
  • instructions on how to deal with error messages.

Implementation:

During this stage the new system is implemented into the working environment, replacing the original system. There are four alternative strategies that can be used to do this: direct; phased; pilot or parallel running.

Staff will need to be trained to use the new system and data from the old system may need to be converted for use on the new system.

Monitoring:

This stage involves monitoring the performance of the new system over an extended period of time to see how well it performs.  Some problems may only become apparent when the amount of data being processed increases above a certain level or at critical times of the year when an above average demand is placed on the new system.

Maintenance:

This stage involves maintaining the new system once it has been installed and is up and running.  This maintenance may well show that some parts of the new system need improving and this will be fed back into the system cycle, resulting in software and hardware upgrades and updates being developed, tested and then implemented.

In the future the business may well develop further and find that even with upgrades the 'new system' no longer meets its needs.  Another investigation and analysis will then take place to identify the new problems and, if feasible, the whole system cycle will start again, resulting in yet another 'new system' being implemented.  The maintenance stage of a system therefore only ends when the a system is is completely replaced by a new system.


A mnemonic  to help you remember the stages of the system cycle: I/ADD/TIMM


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