Structured analysis uses a series of phases, called the systems
development life cycle (SDLC), to plan, analyze, design, implement, and support an
information system. Although structured analysis evolved many years ago, it remains a
popular systems development method. Structured analysis is based on an overall plan,
similar to a blueprint for constructing a building, so it is called a predictive approach.
Structured analysis uses a set of process models to describe a system graphically.
Because it focuses on processes that transform data into useful information, structured
analysis is called a process-centered technique. In addition to modeling the processes,
structured analysis also addresses data organization and structure, relational database
design, and user interface issues.
A process model shows the data that flows in and out of system processes. Inside
each process, input data is transformed by business rules that generate the output.
Figure 1-26 shows a process model that was created with Visible Analyst, a popular
software development tool. The model, which represents a school registration system,
is a called a data flow diagram (DFD) because it uses various symbols and shapes
to represent data flow, processing, and storage. You will learn more about DFDs
in Chapter 5, and you can view a
Video Learning Session that explains
DFDs and how they are used as
modeling tools.
Structured analysis uses the SDLC to
plan and manage the systems development process. The SDLC describes
activities and functions that all systems
developers perform, regardless of which
approach they use. In the waterfall
model, the result of each phase is called a
deliverable, or end product, which flows
into the next phase.
Some analysts see a disadvantage
in the built-in structure of the SDLC,
because the waterfall model does not
emphasize interactivity among the phases.
This criticism can be valid if the SDLC
phases are followed too rigidly. However,
adjacent phases usually interact, as show