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May 25, 2012

Six Sigma Mistake Proofing

Mistake Proofing (or Poka-Yoke as it is known in Japan) is one of several control concepts where the solution is not dynamic by nature, as is the case with a closed loop feedback control system. It should be noted that poka-yoke is very consistent with the fundamental aims and philosophy of Six Sigma and has wide applicability in manufacturing, engineering, and transactional processes. It involves actions designed to eliminate errors, mistakes or defects in our everyday activities and processes. The methodology involves complete understanding of the cause and effect relationship and identification of the simplest remedy that can be applied to eliminate the occurrence of that particular error in the future. Sometimes this involves an addition of a simple feature, the creation of a check list, a change in the sequence of operation, a highlighted field on a form, a software message that reminds the operator, or some other way of helping to ensure that mistakes are going to be totally eliminated or substantially reduced. Often, Mistake-Proofing focuses on errors produced by humans, whether it is the machine operator, the person filling out a form, or someone packing materials, etc. While this source of error can be large, it is also possible to apply Mistake-Proofing methodology in many other aspects of our business. The emphasis should be put on modifying processes so those mistakes are impossible to make, instead of blaming employees for making mistakes. The point is we must improve all aspects of our Business to be robust to mistakes or errors, no matter what the source. The traditional application of Mistake-Proofing is in a production environment where a change is made to an assembly sequence or a tool to prevent an error from being made. Examples include: o A stop is added to a drill press o A hydraulic ram is added to align a component during assembly o A lever is designed into an assembly fixture to index the part o A pin is added so the part cannot be installed backwards Mistake Proofing is the primary form of Control for transactional procedures in that it can be used to prevent a process from going out of control or to bring a process back into control. Some examples include: o Fields on a data entry form are highlighted as being critical o An authorization procedure is introduced to control spend o A check list is created to ensure all items are taken into account when planning a training session o A new policy is developed to ensure that expense claims are completed properly