Construction Operations Management Management of Information Systems
Data Flow
Data flow analysis is a well established methodology and has been used for management
information flow in construction organisations. Other exponents of the data flow concept have
modelled the regional office and site based information systems of a large contractor and an
operational integrated data management system for a house building organisation.
Systems analysis develops understanding of the flow of data through a system. Data flow
diagrams are produced by analysing the progressive transformation of data throughout the
system. Each transformation represents a process which is shown as a circle in the data flow
diagram and lines joining the circles represent the flow of data between processes. Data flow
diagrams (DFDs) are made up fiom four symbols as shown in Figure 1.1 together with an
illustrative example. These four symbols enable a picture of the system to be drawn without
commitment as to how it will be implemented. A data dictionary containing a concise
definition of each element is constructed as data are identified. When the system has been
totally described in terms of data, data transformation processes shown in the data flow
diagram are organised into a topdown hierarchical control diagram. Finally the functions
performed in each process are described using structured English to aid program coding.
An output orientated design approach has the advantage of producing minimal systems in
which the precise scope of a system is defined together with the correct maintenance of data.
Everythmg that appears as output has to be entered into the system at some point as input or
has to be generated fiom some input. By working backwards fiom the outputs the minimum
database and inputs for a new system can be determined. The final systems must produce
answers that agree with the real world and any data that is required to be accurate must be
frequently used. A feedback mechanism must ensure that data is constantly changing to reflect
the updated position.
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