PDCA/Deming cycle illustration (credits: [4,5])


The Plan-Do-Check-Act cycle or Plan-Do-Check-Adjust methodology (also known as Deming cycle or Shewart cycle) is an abstract iterative-incremental procedure model, defined to find a solution to a problem by continuously improving the status quo.


Do you like to watch movies about the wild west? I really do, the movie Young Guns from 1988 is just amazing.

All this outlawry and anarchy mixed with the enthusiasm and hope of a better live is such an illustrious mixture. But would you really want to have lived in this era? With a non-existing infrastructure, brownish drinking water with living ingredients, bad teeth issues, no doctors available nearby and a life expectancy of 30 to 45 years?

The same comes to my mind when I look at today’s startup companies. A lot of John Wayne mentality, wishful thinking and overwhelmingly positive emotions .. at least until the first big bill or first contractual penalty arrives; Shoot first – think later.

A systematical roadmap with well defined business processes to success usually doesn’t exists. Business plans were way too often just created to attract Angel investors. Quality management and a properly analysed way to success? Just an academical myth. The harsh reality is simply clapped away.


There is a simple German proverb, that fits quite well for iterative-incremental problem-solving methods.

Man kann es schnell machen, oder man kann es richtig machen.“, which means that you can get something done fast, or you can get something done correctly. A mutual exclusion. The intention of the saying is that solutions will need time to improve.

A first fast solution is usually unsatisfying and consequences for an unprofessional time-to-market view will be paid in the maintenance phase later on. Technical depts and reputation-loss are high-priced aftereffects.

The US-American physicist, engineer and statistician Walter A. Shewart (1891 – 1967) initially created in 1939 a three-step procedure model to continuously improve the quality of work (“Specification → Production → Inspection”).

W. Edwards Deming (1900–1993) improved this model by generalizing the steps and by inclusion of an additional step (“Act/Adjust”), that shall underline the continuous improvement semantics of the model. This is the model we now know under the terminus PDCA-cycle or Deming-cycle.


In the planning phase the objectives and processes should be determined and established. Conceptual process specifications shall be created or modified based on analysis of the problem to solve.

For software engineering processes this usually means the phase of requirements analysis, that will take place together with the project’s stakeholders.


In the doing phase a prototypical implementation of the conceptual specification shall be created, accordingly modified and optimised.


In the checking phase the results of the prototypical implementation shall be evaluated and internally tested against the conceptual specification.

Act (Adjust)

In the acting phase or adjustment phase, the overall processes of the conceptual specification will be improved, based on the results of the checking phase and its review.


The PDCA-cycle is a classical iterative-incremental method for problem-solving, whereas the solution is continuously improved to suit the actual problem.

Just like in more specific iterative-incremental procedure models, it’s usually a good practice that your solution increments are incrementally versioned.


  1. https://en.wikipedia.org/wiki/PDCA
  2. https://en.wikipedia.org/wiki/Walter_A._Shewhart
  3. https://de.wikipedia.org/wiki/William_Edwards_Deming
  4. https://slidehunter.com/powerpoint-templates/plan-do-check-act-powerpoint-template/
  5. https://creativecommons.org/licenses/by/4.0/

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