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Top 20 Lean Six Sigma Interviews Questions and Expert Answers

Anita Adiraj

Anita Adiraj

Last updated 17/05/2023

Top 20 Lean Six Sigma Interviews Questions and Expert Answers

So, you have been working in the field of Quality Management for quite some time now, and you feel that it’s time to start earning a little more than you are now. In order to add something fresh in your CV, you learn all about Six Sigma. The next part is sitting for an interview, and here’s where you get a little nervous. Isn’t it?

Well, Let me tell you, that’s completely natural. No matter how confident we are about ourselves or how much of corporate experience we have, interviews always give us a little heebie-jeebies. And on top of everything, you just learned a new skill! Who knows what kind of Lean six sigma interview questions and answers they are going to ask you?

To know that, there’s a little secret you need to know. No matter if you are a Six Sigma Green Belt Certified, Six Sigma Yellow Belt Certified of Six Sigma Black Belt Certified, at the interview table the part interviewers really love to ask you about is the basics of Six Sigma. Hence, we have fetched out 20 most commonly asked Six Sigma interview questions for you. Have a look!

1. What is Six Sigma?

Ans. Six Sigma is a set of techniques and tools for process improvement. Six Sigma strategies seek to improve the quality of the output of a process by identifying and removing the causes of defects and minimizing impact variability in manufacturing and business processes.

It uses a set of quality management methods, mainly empirical, statistical methods, and creates a special infrastructure of people within the organization who are experts in these methods. Each Six Sigma project carried out within an organization follows a defined sequence of steps and has specific value targets, for example: reduce process cycle time, reduce pollution, reduce costs, increase customer satisfaction, and increase profits.

2. What are the different variations that are used in the Six Sigma process?

Ans. Mainly 4 variations are used in six sigma process:

  • Mean: This measurement is only useful for a particular application and the values are calculated. In this process, the variations are measured and compared using the average techniques of mathematics.
  •  Median:  This process is initiated by identifying the highest and the lowest values and then divide the value by 2. In this process, the variations are measured and compared by taking the midpoint the data set range.
  •  Range: This process depends on the highest rate and lowest values for a specific data range.
  •  Mode:  Mode is the most occurred values in a given data set range.

3. What is the difference between the Six Sigma DMAIC and DMADV methodologies?

Ans. The DMAIC project methodology has five phases:

  • Define the system, the voice of the customer and their requirements, and the project goals, specifically.
  • Measure key aspects of the current process and collect relevant data; calculate the 'as-is' Process Capability.
  • Analyze the data to investigate and verify cause-and-effect relationships. Determine what the relationships are, and attempt to ensure that all factors have been considered. Seek out the root cause of the defect under investigation.
  • Improve or optimize the current process based upon data analysis using techniques such as the design of experiments, poka-yoke or mistake proofing, and standard work to create a new, future state process. Set up pilot runs to establish process capability.
  • Control the future state process to ensure that any deviations from the target are corrected before they result in defects. Implement control systems such as statistical process control, production boards, visual workplaces, and continuously monitor the process. This process is repeated until the desired quality is achieved.

On the other hand, DMADV methodologies five phases are:

  • Define design goals that are consistent with customer demands and the enterprise strategy.
  • Measure and identify CTQs (characteristics that are Critical To Quality), measure product capabilities, production process capability, and measure risks.
  • Analyze to develop and design alternatives
  • Design an improved alternative, best suited per analysis in the previous step
  • Verify the design, set up pilot runs, implement the production process and hand it over to the process owner(s).

4. Explain the concept of the Fishbone diagram.

Ans: Fishbone or Ishikawa diagram is a visualization tool for categorizing the potential causes of a problem in order to identify its root causes.

5. What are the key principles of Lean Six Sigma?

Ans. The key principles of Lean Six Sigma include focusing on customer value, process improvement through data-driven decision making, reducing process variation, and fostering a culture of continuous improvement.

6. What is the difference between load test and performance testing?

Ans. Performance Testing is a type of software testing that can be carried out to measure the system performance in terms of sensitivity, reactivity, and stability under a particular workload.

On the other hand, The load testing process is a process of putting your demand on a software system or computing and measuring its process.

7. What is the role of a Green Belt in Lean Six Sigma?

Ans: A Green Belt is an individual trained in Lean Six Sigma methodologies and tools. They typically lead smaller process improvement projects or assist Black Belts in larger projects. Green Belts work on improving processes, collecting data, and implementing solutions to drive improvements.

8. What is a Top-down approach in the six sigma process?

Ans: The top-down approach is one of the processes within the Six Sigma implementation. This approach is aligned with business strategy and customer needs. Although, the major disadvantage of this process is its scope is very broad and at the same time it is difficult to execute it in a specified amount of time. 

9. Explain what do you mean by FMEA?

Ans: FMEA is an acronym for Failure Modes and Effect Analysis. FMEA is a risk assessment tool, that evaluates the severity, occurrence, and detection of risks to prioritize the most urgent ones.

10. What are the three steps for Root cause analysis?

Ans: The 3 steps for Root cause analysis are:

  • The Open step: In this step, all the team members gather together and do a brainstorming session on all possible scenarios.
  • The Narrow step: They narrow down all the possible explanations and scenarios are to an extent considering the current performance.
  • The close step: The project team validates all the narrowed down explanations for the current performance.

11. What is the main difference between Lean and Six Sigma?

Ans: Six Sigma follows the DMAIC methodology to reduce waste. On the other hand, Lean uses these following 7 steps:

  1. Overproduction: This occurs when products are being produced but there is no customer to demand it.
  2. Waiting: If there is a time lag after every step of production, no value is being to the project in the meantime.
  3. Transport: This happens when products are being moved in an inefficient way.
  4. Motion: This one denotes poor work standards and employees being involved in inefficient activities between tasks.
  5. Over-processing: This takes place when you spend too much time in producing a product.
  6. Inventory: When your inventory level is too high and you have too much work in progress, this kind of waste takes place.
  7. Defects: This is the number of times when employees spend identifying and fixing production mistakes.

 or  Lean focuses on eliminating waste, improving flow, and maximizing customer value, while Six Sigma focuses on reducing process variations and defects. Lean aims for speed and efficiency, while Six Sigma aims for quality and consistency. However, both methodologies are often used together to achieve operational excellence.

12. What is the significance of statistical analysis in Lean Six Sigma?

Ans: Statistical analysis plays a vital role in Lean Six Sigma by providing insights into process performance, identifying root causes of defects, and validating improvement efforts. It helps in making data-driven decisions, measuring process capabilities, and monitoring the impact of process changes.

13. What is the difference between Cpk and Ppk?

Ans: Cpk stands for process capability index. It measures how close a process is running to its specification limits, relative to the natural variability of the process.

On the other hand,  Ppk stands for a process performance index that verifies if the sample has been generated from the process is capable of meeting Customer CTQs or not.

14. Name some Lean Six Sigma tools.

Ans: Some Lean Six Sigma tools are:

  • Kaizen
  • Poka-yoke
  • FMEA
  • Value Stream Mapping

15. What does DFSS stand for in the six sigma process?

Ans: DFSS stands for Design For Six Sigma. It is a business process management method related to traditional Six Sigma and is used in many industries, like finance, marketing, basic engineering, process industries, waste management, and electronics.

16. What is a data collection plan?

Ans: A data collection plan a plan to collect the necessary data. The main reason to collect data is to understand the current process and portray possible improvement suggestions. The data can be collected from three different primary sources they are as follows:

  1. Input: input is where the data generation.
  2. Process: the process is the execution steps where the factors like efficiency, time requirements, cost, defects are taken into consideration for process improvements.
  3. Output: it is a straight measurement of efficiency.

17. Explain the difference between a Histogram and a Boxplot.

Ans: A Histogram represents the frequency distribution of numeric data, while a Boxplot summarizes the important aspects of continuous data distribution.

18. What is VSM?

Ans: VSM stands for Value Stream Mapping. This is a methodology used to eliminate wastes from a process and map the flow of information required to deliver a product or service.

19. What is MSA?

Ans: MSA stands for Measurement System Analysis. One can use MSA to check if a measurement system is accurate. It evaluates a system’s accuracy, precision, and stability.

20. How to develop a SIPOC process map?

Ans: SIPOC stands for Suppliers Input Process Output Customers.

It defines that a process can be summarized as a series of consecutive steps and activities that are executed in a timely manner to get a definite output. 

Bonus Six Sigma Interview Questions and Answers for You

* How do you identify and prioritize improvement opportunities in Lean Six Sigma?
Ans: Improvement opportunities can be identified through various methods such as process mapping, value stream analysis, customer feedback, and data analysis. Prioritization is typically done based on factors like impact on customers, potential cost savings, and alignment with strategic goals.

* How do you sustain improvements made through Lean Six Sigma?
Ans: Sustaining improvements requires establishing control measures and monitoring key process indicators. This can include implementing standard operating procedures, providing training to employees, conducting regular audits, and engaging stakeholders to ensure continuous adherence to improved processes.

* Can you explain the concept of the "Voice of the Customer" in Lean Six Sigma?
Ans: The Voice of the Customer (VOC) represents the needs, expectations, and requirements of the customer. In Lean Six Sigma, capturing the VOC is crucial for understanding customer preferences, identifying critical-to-quality characteristics, and aligning process improvements to meet customer expectations.

* How do you handle resistance to change during Lean Six Sigma implementation?
Ans: Resistance to change is common during process improvement initiatives. To address it, effective change management techniques should be employed, such as clear communication of the benefits of change, involving stakeholders early on, providing training and support, and demonstrating visible leadership commitment to the improvement efforts.


So, we guess that should help you out during your big hike. Do you know what else can help you? A Six Sigma certification! Go for one, and thank us later when your Six Sigma Certification proves to be a real sixer!

Remember, these are just sample questions and answers. It's important to thoroughly prepare for your interview by studying Lean Six Sigma concepts, methodologies, tools, and real-world examples to provide comprehensive and tailored responses.

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She is the most experienced person in our writer?s forum. Her write-ups about IT Service Management have been the favorite ones of our readers in the past years. Amruta has worked closely with a lot of big farms and showed them how to utilize the ITIL framework to an organization?s supply chain management fruitfully. Her work areas mainly include ITIL Consulting & Implementation, GAP Analysis, ISO Audits, Process/Service Improvement Using Lean Six Sigma, Process Definition, Implementation & Compliance, Process Hygiene (ISO 20000), Quality Assurance & Program Governance.



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