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4.03 - Input / Output Analysis


Input / Output analysis is a method of generating necessary ingredients needed to produced desired results.

Firstly, the Process must be defined, then the required Outputs identified and finally all the inputs required to generate the outputs listed. This is shown by an example below. Note that a Control System monitors the key outputs or Measures of Performance and manipulates one or more inputs to keep the outputs on target.


1 - Process: Assembly Activity

Identify Process

2 - Identify Desirable Outputs

Identify Desirable Outputs

3 - List all required Inputs

List Required Inputs to get the outputs

Some key points are:-

Definition of System (Subject)

  • Be specific
  • Consider where to stand (Viewpoint)

Sub-divide the system to the lowest level of key processes

  • Do not complicate - simplify
  • Do not leapfrog to solution

Limit Analysis to Single Form

  • Material flow
  • Information Flow
  • Think Hardware
  • Look for Boundaries

Synthesize the Solutions

  • Look for loose ends

Input / Output diagrams may be linked together to show where inputs are used, where outputs go and the interdependency of processes.


  • All outputs must be required (that is, they must go somewhere!)
  • All inputs must be available
  • All interfaces must be clearly defined when setting responsibilities for design (Interface below shown as dotted line)

Synthesise the Solutions

Further Reading