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Stepwise Refinement

Stepwise Refinement

Stepwise Refinement

Stepwise Refinement is the process of breaking down a programming problem into a series of steps. You start with a general set of steps to solve the problem, defining each in turn. Once you have defined each of the steps you then break the problem down into a series of smaller sub-steps. Once this is complete you keep on going until you have described the problem in such a level of detail that you can code a solution to the problem.

Stepwise refinement can be represented diagrammatically as such:

Video Tutorial

Advantages & Disadvantages

Advantages of step-wise refinement

  • By breaking the problem down into steps it is easy to get  good understanding of the scale of the problem. As a result less time and resources will be required to solve the problem.
  • Many of the design decisions can be made during the stepwise refinement process, making it faster to make changes than after coding
  • Large projects can be broken down and certain components issued to different developers.
  • The overview makes the project easy to manage.


  • Investigatory projects cannot always be developed from the top-design
  • Stepwise refinement does not easily allow for projects to evolve during the development as a result of internal or external factors.


Activity : Going Food Shopping

Use Stepwise Refinement to break down the process of going food shopping into levels of detail until you would be able to write a ‘shopping algorithm’.