2. • The method for developing systems is called
the system development cycle (or system life
cycle).
• It consists of the five broad stages of:
• understanding the problem
• making decisions
• designing solutions
• implementing
• testing, evaluating and maintaining
• Often, in the development of a system, there is
a good reason to return to a previous step.
4. • Before a system can be planned, the exact nature
of the problem must be understood.
• This may involve redefining the problem and
identifying its key elements.
• A preliminary investigation determines whether a
minor adjustment to the present system will solve
the problem or a new system is necessary.
• Data must be collected in order to assess
feasibility and promote understanding.
5. • There are several methods of data collection
including interviews and surveys (see Table 3.1;
p.92)
• When collecting data it is important to be aware
of:
• bias
• reliability
• validity
• The requirement report is a statement about the
needs of the new system.
• It outlines the aims and objectives of the new
system and how it will solve the problem.
6. • The requirement report also provides an overview
of the new system in terms of data/information to
be used, the information processes and I.T.
required.
• If the preliminary investigation recommends
further examination, then a project plan is
developed.
• A project plan organises the project by specifying:
• who
• what
• how
• when
7. • This means that it identifies all the tasks, who is
responsible for them, any I.T. they will need and a
timeframe for completion.
• It is in this planning stage that a Gantt chart is often
utilised.
• Gantt charts are popular because they quickly
detail all the key aspects of the project and assign
them completion times.
• A Gantt chart is a bar chart with each bar
representing a task to be completed. (Fig 3.2, p.94)
8. • Each potential solution is developed using a
requirement report and the scope of the problem.
• The scope of the problem places constraints on
the new system.
• A feasibility study is designed to look at various
constraints and make recommendations.
• It DOES NOT attempt to find detailed solutions.
• Feasibility studies examine key criteria including:
• economic (money)
• technical (I.T.)
• schedule (time)
• organisational (people)
9. • Implementing a new system requires conversion
and training.
• Conversion involves changing from the old
system to the new.
• The actual method chosen depends upon the
nature of the work and the characteristics of the
new system.
• There are four main methods of conversion:
• direct
• parallel
• phased
• pilot
10. • Direct conversion involves an immediate change
to the new system.
• Though there are minimal costs it is not popular
because there is no time for ‘live’ testing or
training.
• Parallel conversion involves the old and new
system working together.
• It means more work in the short term, but allows
users to familiarise themselves and have a ‘safety
net’.
• It also allows the installers to troubleshoot any
difficulties.
11. • Phased conversion involves the gradual
implementation of a new system.
• Modules are introduced and, as they are
successful, more are implemented.
• Phased is sometimes confusing as people are not
sure which system they are using.
• Pilot conversion involves implementing the entire
system, but only in certain locations.
• If the pilot scheme is successful then it is
implemented in all locations.
12. [ Complete Figure 3.9 from page 107]
• There are many design tools used to describe the
information processes within an information
system.
• Some of these diagrammatic tools include:
• context diagrams
• data flow diagrams
• system flowcharts
13. • A context diagram is a graphical method of
representing an entire system using a single
process together with inputs and outputs.
• E.g. Using a system to find a book in the library
[use Fig. 3.5, p.101]
• The process is indicated by a circle, data flows by
arrows and external entities by rectangles.
14. • Data flow diagrams are similar but they describe
the system in more detail.
• They can have multiple processes and they also
have an open-ended rectangle to indicate external
storage.
• E.g. [Figure 3.6 , p.102]
• A system flow chart is a graphical method of
representing both the flow of data and the
sequence of the system.
• A flowchart also shows the hardware used as well
as the processes.
15. • It uses standard flow charting symbols, plus
specialised symbols for peripheral devices.
• Each symbol contains labels and is linked by lines
called flowlines.
• Flowlines do not need an arrow if the direction is
top to bottom.
[Draw Table 3.5 , p.103]
• E.g. this is a system flowchart for finding a book
in the library.
