Six Sigma (6σ) is a set of techniques and tools for process improvement. This data-driven and disciplined methodology can be used in any processes from manufacturing to transactional and from product to service. It was first introduced by Bill Smith while he was working in Motorola in 1986 and over the years it has gained popularity in different industries and sectors for business improvement.

There are a lot of advantages in using Six Sigma and its positive effects have been the driving force in the effective functioning of many businesses. This is the reason why Six Sigma professionals are still in great demand in various industries. If you are appearing for a Six Sigma job interview, the following commonly asked questions (with answers) will help you to be well prepared.

Here is the top list of Six Sigma Interview Questions and Answers that should be in your to do list before appearing for six sigma interview.

Q1. What is meant by COPQ in Six Sigma?

Cost of Poor Quality (COPQ) is the cost caused through producing defects.

Q2. What is the definition of DPMO or DPPM?

DPMO is Defects Per Million Opportunities and DPPM is Defective Parts Per Million

Q3. What is Pareto Principle?

The Pareto principle (or the 80/20 Rule) states that, for many events, roughly 80% of the effects come from 20% of the causes

Q4. Name some of the Quality Management tools in Six Sigma

There are a number of quality management tools. Some of them are cost-benefit analysis, CTQ Tree, SIPOC analysis, COPIS analysis, and Taguchi methods. (Name at least five)

Q5. Name the different kinds of variations used in Six Sigma?

The different kinds of variation are — mean, median, range and mode.

Also Read>>How Six Sigma Certification Has Become a Key Requirement!!

Q6. Who forms the part of Six Sigma implementation team?

The Six Sigma implementation team usually consists of the following members:

  1. Six Sigma Deployment Leader
  2. Six Sigma Champion
  3. Six Sigma Master Black Belt (MBB)
  4. Six Sigma Black Belt (BB)
  5. Six Sigma Green Belt (GB)
  6. Six Sigma Yellow Belt (YB)

Q7. What is the difference between the Six Sigma DMAIC and DMADV methodologies?

The DMAIC methodology, instead of the DMADV methodology, should be used when a product or process is in existence at your company but is not meeting customer specification or is not performing adequately.

The DMADV methodology, instead of the DMAIC methodology, should be used when:

  • A product or process is not in existence at your company and one needs to be developed
  • The existing product or process exists and has been optimized (using either DMAIC or not) and still does not meet the level of customer specification or Six Sigma level

Q8. Can you explain the concept of fish bone/ Ishikawa diagram?

It is a visualization tool for categorizing the potential causes of a problem in order to identify its root causes.

Q9. What is load testing process?

It is the process of putting demand on a software system or computing device and measuring its process

Q10. What level of understanding do you have regarding the statistical tools?

This should reflect the skills that you have regarding the statistical tools with respect to Six Sigma. Be honest while answering the question.

Q11. What is the difference between Cpk and Ppk?

Cpk is process capability index, which measures how close a process is running to its specification limits, relative to the natural variability of the process and Ppk is process performance index, which verifies if the sample that have been generated from the process is capable of meeting Customer CTQs (requirements).

Also Read>> Which is Better — Lean, Six Sigma or Both?

Q12. Can you explain standard deviation?

Standard deviation indicates the degree of variation in a set of measurements or a process by measuring the average spread of data around the mean.

Q13. What is process sigma calculation?

Process sigma is a measure of the variation in a process relative to customer requirements.

Q14. What is the 1.5 sigma shift?

The 1.5 sigma shift adjustment takes into account what happens to every process over many cycles of manufacturing.

Q15. What is Regression? When is it used?

Regression Analysis is a technique used to define relationship between an output variable and a set of input variables.

There are several types of regression like Simple Linear Regression, Multiple Linear Regression, Curvilinear Regression, Logit Regression and Probit Regression etc., which caters to a variety of requirements based on the type of underlying data.

Q16. What is the difference between defect and defective?

A defect is any non-conformance of the unit of product with the specified requirements. A defective is a unit of product which contains one or more defects.

Q17. What is the difference between Process Report and Product Report?

Process Report is used with continuous data that follow a bell curve distribution, while Product Report applies to discrete data and therefore can be used for all type of distributions.

Q18. Explain FMEA

FMEA is a qualitative and systematic tool, usually created within a spreadsheet, to help practitioners anticipate what might go wrong with a product or process.

Q19. What are X bar and R charts?

They are a set of two charts, which is the most commonly used statistical process control procedure used to monitor process behavior and outcome over time.

Q20. Explain Flow charting and brain storming?

A flowchart is a diagram displaying the sequential steps of an event, process, or workflow. Brainstorming is a technique used to quickly generate creative or original ideas on or about a process, problem, product, or service.

Q21. What is Lean Six Sigma?

Lean Six Sigma is a performance improvement methodology that involves removing stuff that do not add value to the process and reducing variation. This philosophy relies on collaborative team effort. Lean Six Sigma contributes to high quality and customer satisfaction.

Q22. What are benefits of using Lean Six Sigma?

The main benefits offered by a Lean Six Sigma process include –

  • Eliminating defects
  • Manage large teams
  • Ensure more efficient business processes
  • Better prioritization of tasks
  • Better project visibility at the team level
  • Increased team productivity
  • Reduced time

Q23. What are the tools of Lean Six Sigma?

Various tools used in Lean Six Sigma include –

  • FMEA
  • Kaizen (continuous improvement)
  • Pareto Chart
  • Poka-yoke (mistake proofing or inadvertent error prevention)
  • Regression Analysis
  • Value Stream Mapping

Q24. What are different quality levels of Six Sigma?

Six Sigma quality level is a methodology to measure the quality of a process. Every sigma level corresponds to a number of acceptable defects per million, and the optimum sigma level is achieved when the process accuracy goes to 3.4 defects per million opportunities. The admissible number of defects per million as per every sigma level is –

1 – 6,90,000

2 – 3,08,537

3 – 66, 807

4 – 6, 210

5 – 233

6 – 3.4

Q25. What is FMEA?

Failure Mode Effects Analysis (FMEA) is a tool to quantify and prioritize risk within a Six Sigma process, product, or system. This tool helps to take the essential steps for mitigating the risk.

Q26. What is SIPOC?

SIPOC is acronym for Supplies, Inputs, Process, Outputs and Customers. It is a tool that uses information from these five segment and creates a process map, providing a high-level overview of a Six Sigma project. Many organizations these days use the opposite acronym COPIS, putting customers first and explaining the value of a customer to the organization.

Q27. What is MAIC in Six Sigma?

MAIC denotes –

Measure – Accounts for quantifying and benchmarking any process using actual data

Analyze – Includes using statistical tools to identify the root cause of any problem

Improve – Focus on solve the root cause of the problem

Control – Involves keeping checks on problems to avoid their reoccurrence and sustain the gains.

Q28. What is DFSS in a Six Sigma process?

DFSS is the acronym for Define for Six Sigma. It is a process improvement system that involves designing or redesigning a service or a product as per Six Sigma quality standards.

Q29. Explain ARMI or RASI.

ARMI is an abbreviation for Approver, Resource, Member and Interested Party. It is a project management tool to identify the personnel involved in a project and their key responsibility areas.

Q30. What is Standard Deviation?

Standard deviation is one of the most common methods to measure any degree of variation in a data set. It measures the average spread of data around the mean most accurately.

Q31. What is a data collection plan?

A data collection plan is used to collect all the important data in a system. It covers –

  • Type of data that needs to be collected or gathered
  • Different data sources for analyzing a data set

Q31. What is MSA?

The full form of MSA is Measurement System Analysis. MSA is used to check if a measurement system is accurate. It evaluates a system’s accuracy, precision and stability.

Q32. What do you know about Top-down approach in six sigma?

It is a process in Six Sigma implementation, which is in line with the business strategy and consumer requirements, and paves way for common understanding and nomenclature. On the other hand, the major disadvantage of this process is that it has a very broad scope, thus is difficult to be executed within a stipulated time.

Q33. What is VSM?

It is the acronym of Value Stream Mapping. This methodology is used to eliminate wastes from a process and map the flow of information required to deliver a product or service.

Q34. What is an affinity diagram?

An Affinity Diagram is an analytical tool used to cluster or organize ideas into subgroups. These ideas are mostly generating from discussions or brainstorming sessions and used in analyzing complex issues.

Q35. Explain the difference between a Histogram and a Boxplot.

A histogram graphical represents the frequency distribution of numeric data, while a Boxplot summarizes the important aspects of continuous data distribution.

These are some of the popular questions that are asked in Six Sigma interviews. Always be prepared to answer all types of questions — technical skills, interpersonal, or methodology. Being prepared and practice are the ways you can be successful in a Six Sigma job interview.

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