It’s been a wonderful privilege to share a few steps in the learning journeys of more than 130,000 students and professionals who have enrolled in my quality and operations courses over the past nine years on the Udemy platform, which recently became part of Coursera.
As a result, I read thousands of comments and questions every year from manufacturing, engineering, and management professionals around the world in all stages of their careers. This volume of feedback helps me identify trends in the marketplace, common gaps in knowledge, and recurring challenges faced by professionals.
Last week, I received a DM from Domingo, a quality engineering professional who is one of more than 4,600 students enrolled in my Certified Lean Six Sigma Green Belt (2026) class. He’s asking a question I hear frequently in one form or another: “Which Six Sigma certification should I get?”
Here’s what he asked:
Mr. Ray, Once I complete this course, which Green Belt Six Sigma exam can I sit for? It’s confusing especially when there are different BOK and I am trying to find and stick to one. Please let me know.
Thanks,
Domingo
In my effort to do more than simply publish content, and to genuinely help people take the next step in their careers, I try to provide thoughtful guidance on every question I receive. Over the years, questions like Domingo’s have challenged me to refine my own thinking and continue developing new skills. Edited for clarity, here’s how I replied:
Hello Domingo,
Thank you so much for taking my Green Belt course. And I agree with you that the world of continuous improvement belts is confusing. And despite what some claim, there is no universally accepted “gold standard” body of knowledge (BoK). The requirements for each belt level are defined by the organization that develops the program.
When I first developed this course in 2022, I studied the bodies of knowledge for every belt program I could find. And from that research, I built my own course with the topics that I believed best represented the needs of an intermediate-level continuous improvement professional. For instance, I skipped topics that most other BoKs include like “the history of six sigma” and “the grandfathers of quality”.
I love studying the industrial revolution and the subsequent evolution of the manufacturing, engineering, quality, and product design disciplines. I’ve watched the The Men Who Built America1 twice in its entirety. It is fascinating material, but not essential on an efficient path toward developing critical continuous improvement and project management skills.
Each year since the initial launch, I’ve implemented major improvements to the course based primarily on feedback from students and other sources. For instance, I now complement the lecture material for 18 different analytical tools with validated Excel templates. These are downloadable resources that you can begin using in your workplace immediately. None of the certification exams, including ASQ, IASSC, SME, and others, require an understanding of how to use Excel to solve relevant problems. Yet, as a professional, that’s probably what you’ll be doing.
All of this to say, here’s what I would recommend:
Take my class. Get to know that material inside and out. These are the tools you’ll need as a manufacturing quality technician, industrial engineer, or CI professional.
Consider which certifications are most recognized and respected within your industry and geographic region. ASQ or IASSC come to mind in my region. Look at your region and decide based on popularity and marketplace credibility. (Without a universal standard, the term “best” is largely subjective.) Then buy their test prep guide and study it at length. The test prep guide solves two problems: it will help you understand the variety and depth of material in their specific exam. And since many exams are open book, it’s important to familiarize yourself with a comprehensive reference book. This will accelerate lookups during the exam.
This is my best advice for building both the credibility that comes from certification and the practical skills that create value in the workplace.
Thanks again for raising such a practical question. Best wishes,
Over the years, I’ve come to believe that professionals are often asking the wrong question. Instead of asking, “Which certification should I get?” a better question may be, “What skills do I need to become more valuable to my employer, my customers, and my profession?”
Certifications can open doors and demonstrate commitment. But it is practical knowledge, problem-solving ability, and the consistent application of improvement tools that create lasting career value.
The most successful professionals I know pursue both: they earn respected credentials and develop the practical skills needed to make a meaningful impact.
RH
Ray Harkins is a senior manufacturing operations and quality professional with 30+ years of leadership experience driving customer-focused performance in high-volume, complex environments. He is currently the General Manager of Lexington Technologies in Lexington, North Carolina. He earned his Master of Science from Rochester Institute of Technology and his Master of Business Administration from Youngstown State University.
He also teaches more than 60 quality, engineering, manufacturing, and business-related courses through the Udemy platform, recently integrated into Coursera. His courses include:
Certified Lean Six Sigma Green Belt (2026)
Quality Engineering Statistics
Reliability Engineering Statistics
Failure Modes and Effects Analysis (FMEA)
Root Cause Analysis and the 8D Corrective Action Process
He can be reached via LinkedIn at linkedin.com/in/ray-harkins or by email at the.mfg.acad@gmail.com.
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