This month’s first question

What are the leverage point principle, sphere-of-influence principle and span-of-control principle?

Our response

In order of scale, from smallest impact to largest:

  • The span-of-control principle is a formal network of direct effect, such as direct reports.
  • The sphere-of-influence principle is an informal network of effect, such as those at lower level or adjacent functions that react without a solid formal line of control.
  • The leverage point principle is the point in an organization that, when influenced or affected, in turn reacts or affects many other points in the organization—and possibly the entire organization.

This response was written by Larry Picciano, ASQ member, Freehold, NJ.

This month’s second question

Can define, measure, analyze, improve and control (DMAIC) be the basis for a quality management system (QMS)? It seems like a force fit—typically, Six Sigma and DMAIC are viewed simply as group facilitation and process improvement.

Our response

The short answer is yes. However, I agree that it seems to be a deliberate use of the DMAIC str ucture to design and develop management systems. Typically, management system standards are developed based on the plan-do-check-act (PDCA) improvement cycle.

ISO 9001:2015, Clause 0.3.2—Plan-Do-Check-Act cycle, states that, “The PDCA cycle can be applied to all processes and to the quality management system as a whole.”1

The standard further provides guidelines on how the PDCA improvement cycle can be applied to develop a management system in an organization:

  • Plan: Establish the objectives of the system and its processes, and the resources needed to deliver results in accordance with customers’ requirements and the organization’s policies, and identify and address risks and opportunities.
  • Do: Implement what was planned.
  • Check: Monitor and (where applicable) measure processes and the resulting products and services against policies, objectives, requirements and planned activities, and report the results.
  • Act: Take actions to improve performance, as necessary.2

Continuous improvement experts have mapped PDCA vs. DMAIC as follows:

Plan = Define, measure, analyze

Do = Improve

Check = Control

Act = Control

Although DMAIC typically is applied to problem solving and improvement, a QMS could be established by deliberately structuring the system using DMAIC. But remember: Just because you can structure a QMS through DMAIC doesn’t mean it’s the optimal approach. As the saying goes, if all you have is hammer, everything looks like a nail.3 PDCA works best for management systems.

Going beyond the intent of this question, this is how I would structure a QMS using lean and Six Sigma methods to maximize the benefits:

While developing the QMS, apply lean concepts to standardize and eliminate waste in the processes. Use Six Sigma (DMAIC) to reduce process variability and further unlock capacity. Remember to look at the value stream as a whole prior to reducing waste and variation—optimizing the overall value stream is more beneficial than just sub-processes. This will help the organization deliver defect-free products and services on time and at the right velocity, meeting customer takt time expectations.

Whatever approach you use, a QMS must help your organization realize financial and economic benefits.


  1. International Organization for Standardization (ISO), ISO 9001:2015—Quality management systems—Requirements, subclause 0.3.2.
  2. Ibid.
  3. Wikipedia, “If All You Have Is a Hammer, Everything Looks Like a Nail,” https://en.wiktionary.org/wiki/if_all_you_have_is_a_hammer,_everything_looks_like_a_nail.


LaFollette, William, “Expert Answers: August 2018,” Quality Progress, August 2018, pp. 8-9.

Quality Training Portal, “Introduction to Lean Six Sigma Training,” https://qualitytrainingportal.com/courses/introduction-lean-six-sigma.

Snee, Ronald D., “3.4 Per Million: Use DMAIC to Make Improvement Part of ‘The Way We Work,’” Quality Progress, September 2007, pp. 52-54.

This response was written by Govind Ramu, program manager, E2E Closed Loop Learning, Google, Mountain View, CA.

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