People are human and cannot be expected to do everthing like a machine,
exactly the same each time. A simple distraction can lead to a part of
their work being done wrong. It is also not necessarily their fault, as
poorly-designed processes that require a great deal of attention can
contribute severely to problems.
Poka yoke is a Japanese term which
simply means mistake-proofing or fool-proofing and implies
designing work and processes such that it is impossible or very difficult
to for people to make mistakes. It is a simple principle that can lead to
Thus, for example, a plate that must be screwed down in one orientation
only could have the screw holes in non-symmetrical positions so that it
can only be screwed in the right orientation. The principle
can be easily used in non-manual situations (where mistakes can have huge
costs associated), for example in a project management process, checklists
may be used at various times in the project to check that particular tasks
have not been forgotten.