Six Sigma Archives -

DPMO

Inventory, Inspection, Review, Suppliers, Supplies

Question

My question concerns the process performance metric DPMO (defects per million opportunities). I want to use this to quantify a particular supplier’s performance. My question is, is the number of defects referred to in the calculation the number of defects produced by the supplier (in which case it would involve data I don’t have access to), or is it the number of defects experienced by the customer (which is us)? I of course can count the number of defects we receive from the supplier, but if this metric is supposed to be based on the number of defects produced by an organization, I would have no way of knowing how many defects are produced by the supplier’s process, but contained within the supplier’s facility. My hope is to be able to characterize the supplier’s process performance in terms of sigma level.

Answer

The DPMO metric is not usually considered a point estimate of the true percent defective in the lot (either at the supplier or customer site). It is a relative performance metric used to equate the observed percent defective from a sample to defective units per million opportunities. If a supplier culls out all the defective units before shipping to you (i.e. perfect inspection system), your internal DPMO would be 0, even if the supplier DPMO is high. If your goal is to characterize the supplier’s process performance in terms of sigma level, you would need their data, as the data you collect internally is just an estimate for the average outgoing quality from the supplier and not their process performance.

Steven Walfish

For more on this topic, please visit ASQ’s website.

Six Sigma Statistical Meaning

Reporting, best practices, non-compliance reporting

Question

I need to understand the statement, “Adding a 1.5 sigma shift in the mean results …….”
I’m used to the bell curve and + /- three sigma.
How does the extra +/- three sigma fit in, and what is this about moving the mean?
Does ASQ have a good book that includes this detail in with basic statistics?

Answer

The idea of 6-sigma leading to a process with 3.4 parts per million defective is not a totally statistical statement. Using the normal distribution, we know that a process that is centered on its mean will have 0.135% of the distribution outside 3 standard deviations on each tail. That same process would have 0.00000010% outside of 6 sigma, which does not lead to the aforementioned 3.4 million parts per million outside. Dr. Mikal Harry in 1992 published a book (see chapter 6) entitled Six Sigma Producibility Analysis and Process Characterization, written by Mikel J. Harry and J. Ronald Lawson. In it is one of the only tables showing the standard normal distribution table out to a z value of 6. Here is where he stated that processes can shift by 1.5 sigma leading to only having 4.5 sigma limits and the 3.4 parts per million outside the “6-sigma” limits. I would suggest you look at ASQ’s Six Sigma Forum Division that will help to better explain the rationale for the shift.

Steven Walfish
Secretary, U.S. TAG to ISO/TC 69
ASQ CQE
Principal Statistician
http://statisticaloutsourcingservices.com

For more on this topic, please visit ASQ’s website.

Six Sigma Black Belt

Chef, Six Sigma Black Belt

Question

I am currently an Executive Chef working that has been taking online classes for Green & Black Belt Six Sigma. I am about halfway through my Black Belt classes and would like to pursue my certifications. However, my company does not have a Six Sigma department and seem to be getting no where on working on a Six Sigma project so I could qualify for the Black Belt certification. Do you have any advice or guidance that could help.

Answer

This is not an uncommon issue with a number of people. What he should look into is to work as a volunteer at some non-profit organization on a Black Belt improvement project. These organizations are always looking for help and this is a win-win for both him and the organization. He will need to talk to them about what Six Sigma is and the type of project he is interested in doing.

Another possibility is to look at his place of work and if there is a part of the job that has to be done but no one likes doing it. If it is a process, then he could follow the DMAIC process and show improvement. This could also serve as BB project if he can show the time savings was greater than 50%.

Jim

Jim Bossert
SVP Process Design Manger, Process Optimization
Bank of America
ASQ Fellow, CQE, CQA, CMQ/OE, CSSBB, CSSMBB
Fort Worth, TX

For more on this topic, please visit ASQ’s website.

SIPOC

ISO 13485, medical devices, medical device manufacturing

Question:

I’m working on a green belt certification and I have a question about SIPOC. What would be the examples of inputs for hospital test facility? The supplier is physician and patient is the customer?

Response:

Hello,

Here’s an approach to consider:

Supplier=doctor

Input= blood sample, urine sample, sample swab

Process =DNA, microbiology, HVLC

Output =test results

Customer =patient

For more on this topic, please visit ASQ’s website.

Six Sigma Case Studies

Suppliers, supplier management

Q: I would like to browse through detailed Six Sigma Case Studies. I do not mind making a payment for detailed case studies in the fields of manufacturing, services and software.
Kindly direct me to the requisite links please.

A: Thank you for contacting ASQ. I received your request for case studies on Six Sigma in the fields of manufacturing, services, and software.

“Six Sigma is an organization-wide approach used to achieve breakthrough improvements tied to significant bottom-line results. Unlike previous TQM approaches, Six Sigma specifies exactly how the organization’s managers s hould set up and lead the effort. Key features are the use of data and statistical analysis, highly trained project leaders known as Black Belts and Green Belts, project selection based on estimated bottom-line results, and the dramatic goal of reducing errors to about three per million opportunities” (taken from The Quality Toolbox, 2nd ed. by Nancy R. Tague)

ASQ has around 300 Six Sigma case studies available online.

A host of additional Six Sigma content is also available.

Six Sigma Standard

DMAIC process

Q: How are the new ISO 13053-1:2011 Quantitative methods in process improvement – Six Sigma – Part 1: DMAIC methodology, and ISO 13053-2:2011 Quantitative methods in process improvement – Six Sigma – Part 2: Tools and techniques standards to be used?

Is it for certifying Green and Black Belts, or what? Are there plans for “registering companies” to the standard? Thanks in advance for your response.

A: The scope of ISO 13053-1:2011 is to “recommend the preferred or best practice for each of the stages of the DMAIC methodology used during the execution of a Six Sigma project. It also recommends how Six Sigma projects should be managed and the roles of personnel involved in such projects. It is applicable to organizations using manufacturing processes as well as service and transactional processes.”

Similarly, the scope of ISO 13053-2:2011 is to “describe the tools and techniques to be used at each phase in the DMAIC approach illustrating them through fact sheets.”

There is no plan at this point to develop documents that have for intent, or scope, to certify Six Sigma Belts or to register companies to the standard.

Michele Boulanger
U.S. TAG to ISO/TC 69 Chair, SC7 Expert

For more on this topic, please visit ASQ’s website.

Design for Six Sigma

Control chart, data, analysis

Q: I am preparing a short training session for my company on the topic of Design for Six Sigma. I am interested in looking at some examples of how other companies or organizations have used DFSS. Is it possible to get case studies from ASQ on this topic?

A: Thank you for contacting ASQ and the Quality Information Center. Design for Six Sigma (DFSS) can be defined as “robust design that is consistent with the applicable manufacturing processes to assure a fully capable process that will deliver quality products” (from The Quality Improvement Glossary by Donald L. Siebels).

For DFSS case studies, please visit ASQ’s website.

Six Sigma Green Belt Projects

Data review, data analysis, data migration

Q: I teach a course called “Statistical Methods of Six Sigma” at an engineering college. I’m preparing students to take the ASQ Certified Six Sigma Green Belt exam if they are interested (it is not a mandatory requirement of my class).

Here’s my question — most of my students already have jobs lined up after graduation. Some of them are going to places where Six Sigma programs are already fully established. I do have one particular student who is expected to implement a Six Sigma program at the company that she is going to. It’s a small company, and they don’t already have a Six Sigma program in place.

If she passes the ASQ Green Belt exam and receives her Six Sigma Green Belt Certification, how does she go about getting a project approved if she’s working for a company that doesn’t already have existing Belts?

A: To ask a Green Belt to implement a Six Sigma program is not only ambitious, but also somewhat risky. Green Belts have the least amount of experience in Six Sigma. Regardless, what this person should be doing is look at the company and decide what a good first project would be with an executive mentor. The candidate should be looking at something that is important to the company and has impact to the business. It should be something that requires some work and is not obvious to just anyone looking at the project.

Q: I think the expert more accurately posed what my real question is: how does a new grad working for a company that doesn’t currently have a Six Sigma Black Belt program find an executive mentor to approve or qualify her project?

I agree that she will need a Black Belt, but who will/can certify her project if there is not an existing Black Belt or Master Black Belt at her place of work? (It is a small consulting firm for medical hospitals).

A: I recommend that she approach her local ASQ Section and inquire about mentors.

Jim Bossert
SVP Process Design Manger, Process Optimization
Bank of America
ASQ Fellow, CQE, CQA, CMQ/OE, CSSBB, CMBB
Fort Worth, TX

For more on this topic, please visit ASQ’s website.

Lean Six Sigma

Reporting, best practices, non-compliance reporting

Q: Can you explain what Lean Six Sigma is to me? I’ve heard of both lean and Six Sigma as individual concepts, but I’m not quite sure I understand the term Lean Six Sigma.

A: The following concise definition is taken from the book The Certified Six Sigma Black Belt Handbook, 3rd ed. by T.M. Kubiak and Donald W. Benbow (ASQ Quality Press, 2016): “Lean-Six Sigma is a fact-based, data-driven philosophy of improvement that values defect prevention over defect detection. It drives customer satisfaction and bottom-line results by reducing variation, waste, and cycle time, while promoting the use of work standardization and flow, thereby creating a competitive advantage. It applies anywhere variation and waste exist, and every employee should be involved.”

For more information on this topic, visit ASQ’s website.