Error elimination

Q: What’s the best way to reduce human error in production?

Submitted via the QP reader survey

A: The old adage "to err is human; to forgive, divine" works well in social interactions, but in the industrial world, human errors can be costly and occasionally result in fatalities.

The lives of a flight full of passengers may depend on an airplane pilot’s alertness and attention to detail. The same attentiveness is necessary for transactional processes in banking and finance; otherwise, organizations may go bankrupt due to human errors.

Remember W. Edwards Deming’s 85/15 rule that says 85% of the problems in any operation are within the system and are management’s responsibility, while only 15% lie with the worker.1 The same thing holds true for human errors. Eighty-five percent of so-called human errors could be prevented by designing an effective system.

  • Human errors may be due to:
  • The system.
  • Lack of skill, knowledge or experience.
  • Carelessness.
  • Willful sabotage.

How many times as a quality professional have you seen human error assigned as the root cause and "retrain the operator" as the corrective action? Has this ever worked? There is a time and place in which proper training or retraining can help reduce errors. But I’ll get to that shortly.

Most of the situations in which an individual could commit an error can be foreseen during the design of a process via a comprehensive review of the system as a whole—person, method, machine, material, measurement and environment. There is no guarantee all possible opportunities can be foreseen, but assembling the right team with the right experience will help identify most opportunities for error.

It’s also necessary to learn from past errors and examine the opportunity for a similar error to occur in your system based on an underlying root cause. There may be a tendency from the team to discount past errors as completely different situations that aren’t applicable to the current one. On the surface, that may seem to be the case. But the root cause may be one and the same.

Given that you can’t foresee all the possibilities, learning from past experiences is key to reducing human errors. And that’s not just your own experiences; it also includes the experiences of your suppliers, customers, competitors and even organizations from completely different industries.

The Japanese have a devoted body of knowledge on this subject called poka-yoke—also known as error-proofing or mistake-proofing—that is a collection of standard solutions for finding and removing a system-induced error in an industrial or manufacturing setting. Several situations in which this may be applicable include:

  • Designing nonsymmetrical parts.
  • Creating features such as drill or dowel holes to prevent variations in a symmetrical assembly.
  • Designing fasteners of the same thread size to prevent the application of incorrect torque.
  • Designing parts that combine two elements—such as a washer head and a screw.2

The initial cost of developing a system to prevent errors may be low or high depending on the situation. You will need to weigh the severity and probability of the error to justify the need.

For situations in which it is cost prohibitive to design a system to prevent errors, you can use a qualified and competent employee with the right attitude to significantly reduce those errors.

Besides designing a system to prevent errors, it’s possible to reduce the number of errors if the workload is planned in a way that distributes it evenly among your employees, thus reducing stress and fatigue.

Organizational culture and an overall emphasis on doing it right the first time can also play a key role in reducing and preventing human errors.

Govind Ramu
Senior manager, quality systems
SunPower Corp.
San Jose, CA

Reference and note

  1. Mary Walton, The Deming Management Method, Perigee Books, 1988.
  2. These examples and others can be found at http://facultyweb.berry.edu/jgrout/pokayoke.html.

Conformance question

Q: Recently, a new firm began auditing our organization, and I’m noticing differences in requirements compared with our previous auditor. At the closing of an annual surveillance audit for a three-year certificate, if a nonconformance is issued at the closing meeting:

  • What is the expectation for response to the auditor for a minor nonconformance and a major nonconformance?
  • How many days are expected for the initial response for each?
  • How many times during the next 12 months should we expect the auditor to revisit the site to verify corrective action for each?

Deborah Magoon
Grand Rapids, MI

A: Clause 8.2 of ISO 9001:2008, internal audits, does not specify or prescribe any time limits. Clause 8.2.2 only requires the management for the responsible area—the process owner—to take corrective action without undue delay.

With regard to audit follow-up visits, this depends strictly on the registrar or other auditing body. Some auditing bodies will follow up on closed corrective action reports during their next scheduled surveillance audit. This allows enough time for the organization to evaluate the effectiveness of the corrective action taken.

In most cases, the auditee is required to complete the correction action report identifying the root cause and the corrective actions taken to prevent a recurrence. This information is assessed by the auditing body to confirm that a root cause was identified and that the action taken matches the root cause. This is normally done in the form of a desk review.

Due to the costs involved and other logistics, it’s rare for any auditing body to want to come out to verify each corrective action taken. This is usually something for the internal audit staff to perform as part of its audit activities.

Bill Aston
Managing director
Aston Technical Consulting Services

Kingwood, TX


International Organization for Standardization, ISO 9001:2008—Quality management systems—Requirements.

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