5 Must Know Questions on Six Sigma!

5 Must Know Questions on Six Sigma!

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Updated on Mar 2, 2022 11:05 IST

You are hired, Welcome aboard! Does this statement not feel like discovering fire?  To get hired, we all suit up our best, arrange our documents and of course, live and relive the probable interview questions. Still, we all feel anxious for an unexpected question cannon-ball that may get shot at us.


How about a Reference Card that we can go through before the interview; a card that has answers to some of the most basic questions that you must know about Six Sigma.

Here is one for a start.

Question1:  Why it is Six Sigma and not Five or Seven Sigma?

Answer:  The number Six represents the standard deviations between the mean of a process and the closest specification limit. If a process is been carried out under these deviation then at maximum there will be only 3.4 defects per million opportunities (including the 1.5σ shift, otherwise its ≈2 defects per million). Beyond these standard deviations, the specification Criteria will not be met and the Sigma value (Z score) will be negative.

Question2:  What are the methodologies used in Six Sigma?

Answer: DMAIC, DMADV and DFSS other Quality Management tools used are Critical-To-Quality Tree, the Process Map, Histogram, Pareto Chart, Process Summary Worksheet, Cause – Effect Diagram, Chi Squared Diagram, Scatter Diagram, Run Chart, and Control Chart


Define: Involves collating requirements from the client and defining an objective for a project.

Measure: Encompasses comprehension of crucial features of the process involved, its prospective scope and relevant data collection.

Analyze: At this stage, data analysis is done to evaluate the defects, their root causes and the effects on the process.

Improve: Required changes are done in the current process to mitigate the causes of defects and to verify & enhance its capability.

Control: This stage focuses on controlling the future process with the solutions analyzed earlier so as to ensure that any deviation in future can be rectified before causing the defect.


Define: It involves outlining goals in accordance with the organizational strategy or client requirements

Measure: At this stage, crucial elements are recognized by methods like Critical – To – Quality along with identification of process capability and mitigation of risks involved

Analyze: Solutions are analyzed and implemented to meet client requirement

Design: An optimum solution design is selected and applied to the process

Verify: New pilot projects are run to evaluate the efficiency of the process and then the process is then delivered to the client



Design for Six Sigma is a method to enhance the capability of a new process that fulfils customer requirements to the best.

 Quality Management tools are utilized by DMAIC & DMADV/DFSS methodology or even outside Six Sigma to augment quality along with risk mitigation.

Question3:   What is the hierarchy of roles that Six Sigma follows?


Six Sigma Certification

Question 4: What’s the difference between Lean and Six Sigma?

Answer:  Lean Approach and Six Sigma basically aim for the same objectives — to enhance the process involved. The Lean approach on the one hand is basically applied to production and manufacturing processes while Six Sigma has a wider implemention cirlce that includes service processes as well. The most significant difference between the two is — Lean focuses on eliminating unnecessary steps in a process as they are the root cause of waste and no value is added to the process by them, whereas, Six Sigma states that waste actually results from variation in the process. Both the methods being correct, are utilized by organizations as a mixed approach of Lean Six Sigma.

Question 5: What are the gaps that can prevent optimum application of Six Sigma methodology ?


Insufficient data availability – It can make the process lengthy to find the root causes that eventually delay the process.

Incorrect project selection – Many organization select projects for Six Sigma implementation because there are an obvious choice or other projects seem to complicated to pick. What they don’t see is whether the projects chosen can be implemented with Six Sigma or not

Not focusing on the voice of the customer – This leads to deviation in the goal and ultimately hampers progress.

Hopping to implementation – Teams working on Six Sigma implementation ususally jump straight to implementation without proper brainstorming and clear goals. This leads to huge time waste and inappropriate implementation.

Neglecting the manpower for change – A Six Sigma implementation plan might look brilliant on paper, but could fail in reality if changes and feedbacks from the manpower is not considered.

Question 6:  Cite some example of Six Sigma organizations?


  • Motorola
  • Mumbai’s Dabbawalas
  • Amazon.com
  • Boeing
  • Dell
  • Ford Motor Company
  • United States Army and United States Marine Corps
  • Wipro
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This is a collection of insightful articles from domain experts in the fields of Cloud Computing, DevOps, AWS, Data Science, Machine Learning, AI, and Natural Language Processing. The range of topics caters to upski... Read Full Bio