Structured Systems Analysis and Design Method

UK government’s standard method for carrying out the system analysis and design stages of an IT development project is Structured Systems Analysis and Design Method . Central Computing and Telecommunications Agency commissioned it in a bid to standardise the IT projects being developed across government departments. Structured Systems Analysis and Design Method could be described as an updated version of the waterfall model, inheriting the design and coding phases from the waterfall life-cycle. It is similar to the principles of Systems Development Life Cycle.

Structured Systems Analysis and Design Method is a structured method used mostly in the analysis and design stages of system development. It is not directly concerned with the project construction, testing and implementation of software. It is a data-driven concept which concentrates on data modelling.Before subsequent phase can begin, a definite set of activities and deliverables that must be accomplished.

Structured Systems Analysis and Design Method(SSADM) adopts the Waterfall model of systems development, where each completed phase is signed off before next phases can begin.

The main aim is to produce systems that satisfy user requirements and delivered on time. Some business benefits must be provided along with the flexibility to adapt to change is the business environment. It revolves around the use of three key modules:

  • Logical Data Modelling,
  • Data Flow Modelling
  • Entity/Event Modelling

Each of these three system models provides a different viewpoint of the same system, and each required viewpoint forms a complete model of the system being designed. The three techniques are cross-referenced against each other to make sure the completeness and accuracy of the application.

Modelling techniques are extremely useful in tackling the complexity found when attempting to analyse and understand a system. Models are also extremely useful communication tools. The data flow shows what processing is done, when, how, where and by whom.

All these captured ideas and concepts are shown to users and clients for clarification and feedback.

SSADM consists of five core modules, which are further broken down into seven stages which are in turn broken down into steps and tasks. The five core modules are

  1. Feasibility study (FS)
  2. Requirements Analysis (RA)
  3. Requirements Specification (RS)
  4. Logical System Specification (LS)
  5. Physical Design (PD)

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