PDCA stands for Plan, Do, Check, Act, and is the basic
principle for continuous improvement.
Planning means understanding what you are
trying to achieve, understanding how things work, focusing in on the
problem, finding root causes and creative solutions and planning their
Doing is not always as easy as it might seem.
It may include training of people and other project management
activities, but the biggest and simplest traps are often last minute
changes. The problem with these is that if things go wrong, you cannot
backtrack to the decision that led to the action and consequently have
to start all over again.
Checking means checking the results and also
comparing them with what you were expecting. When things go wrong and
good results are not found, this is the part where courage, honesty
and integrity is required to stick to the process. The key question
when things go wrong is 'Why'. With a well documented process you will
be able to go back to the exact point where an incorrect decision was
Acting means acting on what you found during
the 'check' phase, which either means holding the gains and
standardizing the process (e.g. within an ISO9000 system) or acting to
learn from the experience and start again at the appropriate place.
PDCA is often called the Deming Cycle or Deming
Wheel, although Deming attributed it to his teacher, Walter Shewart
and called it the Shewart Cycle, which properly is Plan-Do-Study-Act
(PDSA), which emphasizes the detailed approach during the Check phase.
cynic's version of PDCA is Please Don't Change Anything.