Each bubble is refined until it does just one thing
The expansion ratio decreases as the number of
levels increase
Most systems require between 3 and 7 levels for an
adequate flow model
A single data flow item (arrow) may be expanded
as levels increase (data dictionary provides
information)
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The progression of creating data flow diagrams
is:
Create a logical DFD of the current system.
Next add all the data and processes not in the
current system that must be present in the new
system.
Finally derive the physical data flow diagram for
the new system.
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Better communication with users.
More stable systems, since the design is based on
a business framework.
Increased understanding of the business by
analysts.
The system will have increased flexibility and be
easier to maintain.
Elimination of redundancy.