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How Would You Compare Lean Six Sigma And ISO 9001 In Quality Systems? Any Advice To New Learners Who Already Have ISO 9001 Knowledge?

I cannot claim to be an ISO 9001 expert, but I can give you the bird’s eye view of the two methods. Lean Six Sigma grew out of a desire for a structured method to reduce defects, reduce variation, reduce waste and improve processes such that they satisfy customer requirements faster, cheaper and better. The idea is that you look at a process with “new eyes” so that you are not confined by “the way things have always been done.

In contrast, the ISO certification process grew out of the need for licensing and governing bodies to be able to certify whether or not a company was doing what they said they were doing. As an example, if a drug manufacturer claimed they were screening a certain raw ingredient for toxins before producing medications, then there had to be a way of determining if that was the case. My understanding is that ISO required manufacturing companies to document their processes and then follow the process that they documented. “Documenting a processes” is basically another word for process mapping, and process mapping is a key step in Lean Six Sigma as a way to build profound knowledge of the process. I think an outcome of the ISO movement was the realization that it’s not enough just to “do what you say you do” because once they mapped a given process, they could “see” lots of opportunity for improvement! So, ISO adopted more “improvement” steps in their approach.

ISO 9001 has these as it’s process steps:

  1. First, you identify your key processes.
  2. Second, you define quality standards for those processes.
  3. Third, you decide how process quality will be measured.
  4. Fourth, you document your approach to achieving the desired quality, as determined by your measurements.
  5. Fifth, you evaluate your quality and continuously improve.

On the flip side, Lean Six Sigma would advise you to prioritize which processes to focus on based on organizational strategy, customer satisfaction and cost of poor quality. The idea is to develop a pipeline of opportunities, tackle the most critical first and develop a culture of process improvement by building the problem-solving muscles of the employees.

Once selected, the DMAIC method would take these 5 steps:

  1. Define: Map the process, isolate the issue to address, define the customer requirements of the process and set a goal
  2. Measure: Baseline the capability of the process in comparison to the customer/business requirements
  3. Analyze: Study both the process and the data collected about the process to understand the root causes of the process issues
  4. Improve: Implement innovative countermeasures to address the root causes of the issues and document the “to be” process
  5. Control: Continue to monitor the process capability and look for opportunities to continuously improve

My main advice to the new learners would be to use Lean Six Sigma and the DMIAC method to accomplish that last ISO admonition of “continuously improve.” There are over 100 years of quality tools built into Lean Six Sigma which is itself a distillation of the “best of the best” quality methods.

I hope that helps!

Elisabeth Swan

Elisabeth is a Managing Partner at, the co-author of The Problem-Solver’s Toolkit and co-host of the Just-in-Time Cafe. For over 25 years, she's helped leading organizations like Amazon, Charles Schwab and Starwood Hotels & Resorts build problem-solving muscles with Lean Six Sigma to achieve their goals.