Six Sigma Interview Questions and Answers Quality Management

Six Sigma has a simple goal to deliver nearly perfect products and services for company transformation to maximize customer satisfaction. Six Sigma has five principles: 

• Customer-focused: The fundamental objective is to deliver the maximum advantage to the consumer, founded on the hypothesis that "the customer is king." To do this, a company must comprehend its clientele their wants, needs, and factors influencing loyalty or sales. To do this, the quality standard must be established according to what the consumer or market expects. 

• Value chain assessment and finding the problem: Describe the processes of a procedure to identify undesirable locations and collect relevant data—set expectations for expected insights as well as data caching objectives and purposes. Check to see if the data is helping to achieve the goals, if more information needs to be obtained, or if data purification is necessary. Identify the issue and its underlying cause. 

• Elimination of defects: Once the issue has been located, the method should be modified appropriately to remove any flaws. Eliminate any process step that doesn't add to the value for the client. Multiple tools are utilized to identify problem areas and outliers if the value chain cannot do so. The bottlenecks in a particular process can be eliminated by removing the outliers and flaws. 

• Involve stakeholders: All stakeholders should participate in an organized process where they can work together to solve complex problems. The group must become proficient in the approaches and guiding principles used. Therefore, specific knowledge and training are needed to reduce the risks of project failure and guarantee that the processes are performing at their peak. 

• Be flexible: Six Sigma calls for flexibility from various angles. The management system of the company must recognize improvements. To eliminate variance, people should be encouraged to embrace systemic changes. The advantages of the six-sigma method should be made known to all levels of employees to inspire them. As a result, people will readily accept the adjustments. 

COPQ stands for Cost of Poor Quality. An organization's cost of poor quality (COPQ) is the cost associated with offering low-quality products and services to its customers. Another way to put it is that it refers to the total amount of losses incurred by the company due to doing things incorrectly. Instances include scrapping, reworking, repairing, and failing to keep a warranty. Organizations use the Cost of Quality to measure the resources used for quality in their processes. Put another way, it is the expense of producing quality products. 

The cost of quality is the combination of good quality and the price of poor quality.

The cost of quality is divided into four categories: 

• Preventive Cost: These are the costs related to services used to prevent failures like training, market research, quality audits, etc. 
• Appraisal Cost: These are the costs focused on discovering the defects like lab testing, good inspection, calibration, etc. 
• Internal Failure: These are the costs focused on the failure of the product to achieve the required quality, like rework, repair, re-testing, etc. 
• External Failure: These costs arise with the rejection of the product after reaching customers, like penalties, warranty claims, etc.

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Measuring performance metrics with accurate methods is critical when working on a Six Sigma project so that you can determine what changes have been made and the value of the changes. It is commonly measured by Defects Per Unit (DPU), Defects Per Million Opportunities (DPMO), Parts per Million Defective (PPM), and Rolled Throughput Yield (RTY). 

DPU (Defects per Unit): It measures the average number of defects per unit. It's found by dividing the total number of defects found by the number of units. 

DPMO (Defects per million opportunities): It measures how often you have made a mistake or flaw (defect) for every chance you had. It can be calculated by dividing the total number of defects found in a sample by the total number of defect opportunities multiplied by 1,000,000. 

PPM (Parts per Million): It measures the number of defective units per 1 million., calculated by simply taking the number of defective units of the same size, dividing that number by the total sample size, and multiplying by 1 million. 

RTY (Rolled throughput Yield): A manufacturing or service process' RTY (or First Pass Yield) measures the chance (or percentage) that a defect-free unit will be produced. For this, you need to map out the steps of a process. 

The Pareto Principle is the simple way to improve the business by identifying the focus area to putting effort and resources to achieve maximum efficiency. It simply states the 80/20 rule; in other words, 80% of the results come from 20% of the effort. For example: 

• 20% of developer's efforts deliver = 80% of the result 
• 20% of the bugs = 80%of the crash 

Those who follow the Pareto Principle in Six Sigma projects know that most problems can be attributed to a small number of causes. Graphing a Pareto Chart in graph form can help teams visualize the pain caused by the significant few problems. By creating a chart, teams are better able to: 

• A quick glance at a process' problems 
• Identify all the obstacles to the process as soon as possible 
• Pay attention to the issues that disrupt the most 

Sig-Sigma is an essential methodology for any business process to bring significant improvement by identifying flaws and weaknesses. Over the years, Six Sigma practitioners have developed tools and methods to reduce defects and waste through control and problem-solving. The widely used Six Sigma tools are: 

• DMAIC: This tool includes five steps, Define, Measure, Analyze, Improve, and Control. A DMAIC process allows continuous improvement in manufacturing methods through data and measurable goals. 
• The five Whys: This method is deployed at the Analyze phase in DMAIC. The five whys work like that, 

1. Write down problems to make the team focus on them 
2. Ask why the issues happen 
3. If not, get the answer, and ask again why? 
4. Repeat the why at least five times to get the correct source of the issue 

• 5S system: The 5S System organizes workplace materials to facilitate easier access and better management. This system eliminates waste that is generated by poor working conditions and workstations that are inadequate. The 5S stands for: 

1. Sort only necessary items 
2. Set all items and label them 
3. Shine your work area by cleaning 
4. Standardize your set standard and sort them 
5. Sustain by executing all the standards by practicing regularly 

• Value Stream Mapping: This tool helps to improve and optimize the flow of materials and information in the organization. It identifies three things,

1. Identify the activities when they are enabled; they add value 
2. Identify the value-added activities 
3. Identify non-value added activities and eliminate them 

• Regression Analysis: It is a statistical tool used to estimate and understand the relationship between two variables by defining a mathematical relationship between input and output variables. Graphing these inputs and outputs helps you visualize patterns or deviations from desired patterns in your workflow.
• Pareto Chart: This is an essential tool of Six Sigma since it helps identify 20% of resources that result in 80% of process mistakes. It gives you a clear indication of which components need your immediate attention. 

Six Sigma aims to deliver quality products to the customer. As well as reducing output variation, it seeks to predict process results. Measuring, analyzing, improving, and controlling are the steps in this process. Variation refers to the amount by which the output deviates from the actual output. The variations used in Six-Sigma are; 

Mean: Mathematical averaging techniques are used to measure and compare the variations. Then, a specific application is measured, and a mean is calculated. 

Median: In this, variations are measured and compared using the midpoint. It is calculated by finding the highest and lowest values and dividing them by two.

Range: It differentiates between high and low values in a given data range. 

Mode: Most occurred values in the given data. 

The Six Sigma team members belong to different departments; however, all work with the same goal to produce a quality service. The Six-Sigma team consists of: 

• Six Sigma Deployment Leader: They set the business objectives and create a successful environment.
• Six Sigma Champion: Project Champions or sponsors are business, function, or value stream managers whose businesses, operations, or value streams are considered high priorities. They ensure process improvements are captured and sustained since they own the business's processes. 
• Six Sigma Master Black Belt: These individuals develop sig-Sigma strategies and supporting tactics based on high-level business goals. The team coordinates and leads cross-divisional value streams like customer service, Research, etc. Moreover, they promote a culture of openness, creativity, and challenge. 
• Six Sigma Black Belt: These are full-time or part-time leaders who guide green belts and other associates through the implementation of projects. They are responsible for technical responsibility to execute specific tasks and ensure that all the changes are implemented and sustained. 
• Six Sigma Green Belt: These are the engine of the projects; the goal of green belts is project execution, team and project structuring, and sharing of best practices. 
• Six Sigma Yellow Belt: After the project has been completed, this team also plays a crucial role in transferring the process improvements from Six Sigma to other parts of the organization.

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DMAIC and DMADV are the two frequently used Six Sigma methods that increase the effectiveness and efficiency of the business process. While the two approaches have some fundamental similarities, they are not interchangeable because they were designed for use in different business processes.

DMAIC stands for Define, Measure, Analyse, Improve, and Control and is used to improve the existing process. It is a reactive and process-focused method that needs a small team continuously working for improvement. It is a corrective approach using statistical and quantitative tools to implement incremental changes. 

DMADV stands for Define, Measure, Analyze, Design, Verify and is used to seek new processes. It is a proactive, customer-focused method that needs a large team to reengineer the services. It is a preventive approach using qualitative tools to implement evolutionary changes. 

The fishbone or Ishikawa concept is a visualization tool to understand the relationship between "cause and effect" to solve an issue. The tool is beneficial since it illustrates the root of a problem or a phenomenon, what factors play a crucial role in causing those problems or phenomena, and how to resolve the situation. An Ishikawa is drawn in the shape of a fishbone, allowing you to understand what drives and affects the relationship you are trying to understand.

When to use the Fishbone diagram? 

• When there are multiple problem causes 
• Identifying the root causes 
• Sort the interaction between factors and effects 
• Initiate corrective action for problems 

Steps to draw a fishbone diagram 

1. Identify and write the problems that need to be analyzed clearly 
2. Draw a horizontal line called spine; at the right end of the spine, draw a box and write the determined problem in a box. 
3. Identify major causes and write them down above and below the horizontal line. These causes are men, methods, machines, materials, measurements, and the environment. 
4. Brainstorm and link the sub-causes to the leading causes 
5. Finally, the fishbone diagram is ready for analysis. Analyze all the possible causes of an effect and use the 5why analysis to identify possible causes. 

The purpose of load testing is to determine a system's Performance under real-life load conditions. This type of testing aims to explain how an application responds when multiple users access it at the same time. Load testing identifies the following conditions; 

• Verify the maximum capacity of an application 
• Verify whether the infrastructure is suitable for running an application 
• Verify the application's sustainability 
• Their concurrent users, scalability categorizes applications, and the number of simultaneous users they can support. 

There are different types of load testing, 

1. Load testing examines the application's reaction time and tests the workload built under typical circumstances. 
2. Stress testing determines the load point at which your application will crash by applying a hefty workload. 
3. Spike Testing  This involves exchanging workload instantly and monitoring application response in real time. 
4. Durability testing exposes the application to the anticipated workload for a long time to see how well it can manage it. 
5. Reliability testing In this test, the workload will gradually increase to see how well the program can handle more work. 
6. Volume testing Aims to test the software's database's data processing capacity and cost-effectiveness by feeding it large volumes of data. 

An approach to Six Sigma involves converting a practical problem into a statistical problem, solving it statistically, and then converting the statistical solution back into a functional problem. There are widely used statistical tools; 

• Gage R&R: You may check the reproducibility and repeatability of continuous measures like pressure, weight, and diameter with the Gage R&R. It assists in determining whether the measurements are accurate. 
• Histogram: The term histogram refers to a snapshot of continuous, numerical data. It helps you identify the spread and center of data much faster. This tool lets you locate maximum data and provides information about maximum and minimum values. 
• ANOVA: One of the frequently utilized Six Sigma techniques businesses employ worldwide is ANOVA, a group of statistical models applied to study mean differences. Simply put, this statistical tool makes comparing two or more means straightforward. 
• Regression: Six Sigma regression is a statistical tool used to determine whether an input and output variable are related. An example of how you can use the device is to determine whether a company's sales revenue and marketing expenditure are related. 
• T-test: Another statistical technique for comparing the average of one sample to the average of another sample is the t-test. The average of one sample can also be compared to a predetermined target using this method. 
• DOE: To ascertain any links between the inputs and outputs, Design of Experiments (DOE) provides a data gathering technique to change the information. This tool can find the best settings after gathering essential data and identifying crucial inputs. 

The standard deviation is the square root of variance measured as a measure of dispersion in a dataset. A standard deviation is calculated by determining each data point's deviation from the mean and taking the square root of that. Standard deviation is often referred to as SD and is indicated by the symbol "σ."

Steps to calculate SD: 

• Calculate the arithmetic mean
• Calculate the squared differences from the mean by (The data value-mean)2 
• Calculate the squared differences' average (Variance = sum of squared differences / the number of observations) 
• Calculate the square root of the variance (Standard deviation = √Variance) 

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Six Sigma's analysis phase is one of its most essential components. The analysis aims to identify defects, errors, and waste within a project and map out exactly what happened. An effective tool for discovering associations between variables in data, regression analysis cannot necessarily show causality. As a result, it has several applications in business, finance, and economics. It is used, for instance, to assist investment managers in valuing assets and comprehending the connections between variables like commodity prices and the stocks of companies that trade in those commodities. 

Regression analysis is most often connected with the analysis stage of the DMAIC (define, measure, analyze, improve, and Control) five-step Six Sigma methodology. DMAIC enables businesses to streamline current procedures and get rid of errors. Regression analysis is one of the various tools used in the Six Sigma analysis phase. 

Lean can also employ regression analysis to identify wasteful regions. It enables both the use of data to make predictions and the measurement of whether outcomes are consistent with expectations when a process variable is altered. 

Defect, any product or service that deviates from the specifications is said to have a defect. A defect does not automatically preclude the use of a good or service, and a defect only signifies that the end product did not turn out strictly as intended. 

Defective, A product or service that is entirely unusable is deemed to be faulty. There are only two options: either each product or service is deemed defective or not.

An item with a fault has one or more defects. Nevertheless, not all damaged things are defective, depending on the flaw's seriousness. 

FMEA stands for Failure Modes and Effects Analysis. FMEA is a proactive strategy for assessing a process to determine where and how it might fail and to gauge the relative impact of various failures to pinpoint the areas of the process that require the most significant improvement. FMEA is used when,

• Improve an existing process. 
• Establishing a new process before putting it into use in a production environment. 
• Looking for quality control (QC) problems that occur within a process. 

The following are types of FMEA 

1. DFMEA (Design Failure Modes and Effects Analysis) 

A DFMEA is concerned with a good or service, and these are often carried out before creating new goods or services or whenever a change is made to their designs. When you do one, you consider potential errors, safety risks, and legal and regulatory difficulties with the finished product. 

2. PFMEA (Process Failure Modes and Effects Analysis) 

A PFMEA examines a procedure. In contrast to a DFMEA, it simply analyzes the final good or service to identify problems with a production process. You'll more frequently take a look at the process's results. Why do these two items vary from one another? Because most goods and services result from several processes rather than a single one. 

3. SFMEA (System Failure Modes and Effects Analysis) 

A system failure mechanisms and consequences study broadly views the entire system. One involves looking at things like how processes and components are related. Problems might arise outside of methods or with particular machines; therefore, an SFMEA can be helpful. They also happen when several machines or processes work together. 

X-Bar and R charts are Six Sigma's most potent quality control tool to monitor the process. They visualize variations, identify problems, predict the range of outcomes, and analyze patterns of process variation. These tools are commonly used in lean six sigma projects during the control phase.  

X-bar chart: It is the average deviation from subgroup values in a process over time. The control limits on the X-Bar account for the sample's mean and center. 

R-Charts: This keeps track of how quickly the process is spreading.  

Quality control charts like the x-bar and R-chart are employed to keep track of a process's mean and variation using samples gathered over a predetermined period. 

Brainstorming is a valuable Six Sigma tool used for problem-solving, evaluating pieces of information, stimulating creativity and developing ideas, and participating in the impromptu discussion. In Six Sigma, brainstorming is used in many ways, 

• It helps to find the root cause of the problems by incorporating with fishbone diagram and 5Whys methods. 
• It helps in creating SIPOC. 
• It helps in creating a process map. 

Tools to keep Brainstorming structured: 

• Affinity Diagram: In affinity diagramming, large amounts of language data are organized according to their natural relationships to create groupings. The affinity diagram can be used to gather many ideas from a group of participants before others' ideas influence them. 
• Fishbone Diagram: The fishbone diagram is one of the simplest yet most effective tools in brainstorming sessions for categorizing the sources of an issue to determine its root causes. 
• Brainstorming Maps: The best way to visualize brainstorming ideas is to use a diagram with a central root and branches radiating. It is a visual thinking tool that aids information structuring, enhancing your capacity for analysis, comprehension, synthesizing, memory, and idea generation.

1. This graphical representation of a process allows you to analyze boundaries and edges, understanding where the product goes. The diagram contains geometric symbols that depict the materials, services, and resources involved in the methods and the directions needed to achieve the result (product or service). 
2. Since the flow chart has the primary mapping function, this tool is essential because it is necessary to measure a process to improve it. 

Symbols used in Flowcharts:

Types of Flowcharts: 

1. Block Diagram: The most straightforward flowchart ever created. It acts as a process sequencing because it consists of blocks and does not include any decision points. It is employed as direct work instructions (ITs) or when a more comprehensive depiction of a process is desired. 
2. Process Flowchart: While it resembles a block diagram, it also has decision points. 
3. Functional Flowchart: This flowchart shows how a process is carried out between sections or areas. This type of flowchart is widely used for functions that don't restrict themselves to a single area. Since the responsible party is identified for each phase, any bottlenecks can be identified. 
4. Vertical Flowchart: Process Diagrams, also called vertical flowcharts, consist of symbols and patterns in vertical columns. It is used in studies of productive processes because it provides speed of filling, clarity of interpretation, and ease of reading.

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The lean SIX Sigma methodology aims to reduce problems, eliminate waste, and improve working conditions to improve customer service. It combines lean six Sigma's tools, methods, and principles to enhance your organization's operations. Globally, businesses have seen dramatic improvements in profitability due to lean six Sigma's team-oriented approach. 

The difference between Lean Six Sigma and Six Sigma are: 

1. Lean Six Sigma is waste-focused, whereas Six Sigma works on variation and any deviation from the target.
2. Lean Six Sigma uses visual techniques, while Six Sigma uses statistical tools to analyze and solution creation. 
3. The Lean solution is documented using a redesigned value stream map, frequently resulting in changes to work instructions and workflows at numerous process phases. In addition, changes in setup procedures and the control plan for observing the process and reacting to variation are included in the documentation of the Six Sigma solution. 

Lean Six Sigma, which enables businesses to use data to reduce process flaws, has emerged as one of the most powerful frameworks for delivering better goods and services while still being effective. The benefits of using Lean Six Sigma are: 

1.  Improve customer satisfaction: Customer satisfaction is one of the crucial metrics to measure the success of any organization. And lean Six Sigma reduces the ratio of dissatisfied customers by identifying the root cause and continues to work towards making products customer satisfaction.
2.  Increase Productivity: The Six Sigma methodology allows organizations to measure time spent on work activities and identify the root causes of productivity issues. Rather than beating around the bushes blindfolded, Six Sigma will assist you by collecting business-critical data from different locations.
3. Reduce project lifecycle: In most cases, enterprises run over the original deadline for a project due to changes in project scope or management policies. An organization implementing the Six Sigma methodology can form an exclusive team that includes professionals from all levels and departments. The team is then responsible for identifying critical factors that can negatively affect the project, causing it to run over its schedule. Once the project manager has discovered the root cause of the problems, they can be assigned to find solutions. As a result, project lifecycle times can be shortened by 35%.
4. Reduce the cost: Problems are reduced by the Six Sigma process to 3.4 defects per million opportunities. An organization will ultimately lower the cost of achieving quality by 20% and boost operational revenue by 50% if it spends less time mending defective items.
5. Time Management: Employers using the Lean Six Sigma technique can assist their staff with time management, leading to more productive staff members and an effective firm. The data principles of Six Sigma can be applied to the SMART (specific, measurable, attainable, results-focused, and time-bound) goals that employees are asked to set. This can be used in three main areas: learning, Performance, and fulfillment.

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The techniques and tools used to achieve the goals of lean Six Sigma are based on the type of analysis in which they will be used, and according to this, there are the following tools, 

1. Process Analysis Tools: These tools describe the process and understand its efficiency.

• Process Map is a graphical representation of the link between the process and decision points. 
• The value stream Map includes the steps of the customer value in the process. 
• Data boxes record the cycle time, resources, value-added time, etc. 
• TAKT time reflects the time allotted to each process. 
• Value-added time is the amount of processing time spent on a single item moving through the process when adding a component of customer value takes place. 
• Kanban visual task scheduling tool. 
• Visual Control signals the process bottlenecks and helps to relieve those. 

2. Visual Analysis Tools: Virtually all problem-solving methodologies use visual analysis tools and techniques. These methods can be applied at various stages, and they are valuable since they are rapid and straightforward to comprehend. They are also great ways to communicate with senior management and the operations or organizations that the solution will affect.

• Histogram 
• Fishbone 
• Pareto chart 
• Scatter diagram 
• Run chart 
• Pie chart 
• Box Plots 
• Check sheets 

3. Project and Team management: Customers and stakeholders must be able to communicate with lean six sigma projects. Numerous methods have succeeded in this area. Organizing and communicating with internal stakeholders, such as team members, might benefit from some of these strategies, some of which are founded on comprehending the viewpoint of external stakeholders. 

• CTQ, i.e., critical to quality, is used to measure the product and the process by the stakeholders. 
• The project charter is a project management document that sets parameters for the activity's scope and authorizes the project. 
• SIPOC  
• Cross-functional team 

The SIPOC acronym stands for, Suppliers, Inputs, Process, Outputs, Customer; all these areas help to create a process map. Each process begins with suppliers offering the process's inputs, which produce the output given to customers. 

Benefit: 

• Define the new process 
• Provide a complete project overview to all stakeholders 
• Initiate problem-solving 
• Keep all the stakeholders on the same page 

How to create SIPOC:  

With the subsequent steps, SIPOC is a table that records the process, output, client, input, and supplier in a table format. 

1. Identify the process for which SIPOC is to be created. 
2. Define the planned steps that typically add value to the inputs to produce consumer outputs. A high-level process flow should only have up to 7 phases; any more makes it difficult to understand. Instead, use an affinity diagram to condense complicated procedures into a handful of essential steps. 
3. List the outputs, like products, services, and information valuable to the customers. 
4. Identify the customers or users of the product. 
5. Determine the inputs, i.e., material and service used by the process to produce. 
6. Identify suppliers 
7. Validate the diagram before moving to the process improvement stage. 

DFSS stands for Design for Six Sigma. The Design for Six Sigma technique aims to increase product and service quality by minimizing variance at the source. The DFSS strategy uses trials and data analysis to design, implement, and improve products and services. Through the development of goods and services that are more useful, effective, efficient, safe, and long-lasting, the aim is to decrease waste across all processes and increase customer satisfaction. 

Benefit:

• DFSS allows improved communication between all stakeholders, including teams and customers. 
• When all designs adhere to the identical procedure and use the same equipment, it is much simpler to create standardization within an organization. 
• By guaranteeing that each project's component serves just one goal, DFSS also contributes to reducing waste. 

ARMI stands for:

Approvers, Sponsor, or business leaders 

Resources, experts whose skills are needed 

Members, team members 

Interested party, team members who need to be informed of project status 

These labels serve as a tool for classifying all the people and their abilities who can contribute to a project's success. ARMI helps the lean six sigma practitioner to identify the stakeholders and create an engagement plan. It also helps to understand different skills and resources early in the project.

The top-down element is associated with problem selection. Teams working on Lean Six Sigma projects solve real-world problems impacting customers and processes. The top-down approach involves a senior manager, a Senior Champion, considering the company's primary business issues and objectives and proposing strategic improvement initiatives. After developing a strategic vision, the Six Sigma Champion identifies processes, CTQs (Critical-to-Quality Characteristics), and opportunities for improvement.

Six Sigma implementation creates shared understanding and vocabulary by aligning with business strategy and customer needs. Nevertheless, due to its extensive scope, this process is challenging to implement within a particular time frame.

VSM stands for Value Stream Mapping. It is a method that illustrates, analyzes, and improves the necessary step to deliver a quality product. VSM is a crucial methodology of lean Six Sigma that tracks the steps from the beginning to providing a service to the customers. Add them

The main objective of Value Stream Mapping is to identify and eliminate waste. There are four elements of the VMS: 

1. Product Flow: The product flow diagram illustrates the material's flow through the process. From raw material to a finished product, how does a finished product become a product that can be sold to consumers?  
2. Information Flow: This explains how the process is managed. 
3. Customers: The first thing to draw on is the VSM that will help an organization understand how frequently product products meet customer needs. 
4. Suppliers: Avoid adding every supplier to the map; add one type of supplier at a time. 

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An affinity diagram is a way to group ideas, opinions, and issues based on their relationships. An affinity diagram is typically used to categorize ideas generated during brainstorming sessions, and it's beneficial for analyzing complex problems. 

The Affinity Diagram is generally used when a problem is new, complex, or unfamiliar, but not when there is a mathematical or structured component. The tool is easy to use and facilitates team collaboration by letting everyone share their thoughts, ideas, and questions. 

Steps of Affinity Diagram: 

1. Identify the issue 
2. Gather the cross-functional team 
3. Do brainstorming sessions with teams to find the cause and solutions and put them into sticky notes. 
4. Gather all the ideas 
5. After getting all ideas, rearrange the notes and put them into categories 
6. Label the category on the top 
7. Continue to brainstorm on new topics or category 
8. Finally, find the issue using the five whys to develop a list of solutions. 

Six Sigma aims to improve the productivity and quality of a project team or organization. Six Sigma uses different charts aids to identify variations between data samples to accomplish this goal, and histograms and box plot is used for graphical representation.  

Histogram: A histogram is a type of bar chart showing a data set's frequencies graphically. In a histogram, the Y-axis (vertical) represents frequency, and the X-axis (horizontal) represents the measured variable. 

Box Plot: This chart graphically represents the five most important descriptive variables for a data set in a box plot. This table has five values: minimum, first quartile, median, third quartile, and maximum. 

Six Sigma projects are measured by customer needs and ensure the organization's internal metrics are met. One of the most critical components of Six Sigma's Define phase is selecting project metrics. Six Sigma metrics are categorized into two metrics 

1. Primary Metrics also called a project CTQ and monitor project success. Primary project metrics are required to ensure that the project needs are quantifiable and controlled during the project. The following characteristics are essential for primary metrics; 

• Should define the objective of the project 
• Simple, measurable, and can be mathematically expressed 
• It can be easily trackable hourly or monthly basis. 
• It can be validated by measurement system analysis. 

Some primary metrics are on-time delivery, customer satisfaction, etc.

2. Secondary Metrics are also known as consequential metrics, and these measures ensure that the process is strengthening and not favoring one metric over another. It implies that a Six Sigma project's secondary and primary metrics are related. Some important secondary metrics are, Rework time, Inspection data, Project cycle time, etc.

Six Sigma metrics are measurement tools used to track the quality process. Here is a list of widely used standard Six Sigma metrics: 

1. Defect Rate: When companies fail to efficiently produce a product's units, defects develop in the production process. You may determine the defect rate by dividing the total number of flaws by the number of units produced over a given period. 
2. Process Cycle Time: The process cycle refers to the time taken by a product to go through the production process. This can be calculated by totaling the manufacturing times for all items and dividing that total by the overall number of products. 
3. Lead Time: Lead time is the period between the day a client places an order and the date that a company ships the goods to the customer. You can determine the lead time by deducting the delivery date from the order placement date. 
4. Process Measurement: This precision measures the inputs in the process. 
5. Process Capability: Process capability is the amount of variance in your production process you can handle before the quality of your product suffers. You can use the highest specification limit to determine process capabilities. The maximum level measurement can attain and yet be deemed acceptable by consumers is known as the upper specification limit. 
6. X-bar: The average number of flaws per unit produced during a given period is known as the X-bar. This measure can be calculated by summing up all the spots over a given period and dividing that total by the overall number of units you produced. 

Performance testing is a type of testing that assess the system's responsiveness, stability, and sensitivity to a given particular workload—this help to evaluate the number of users working with the system simultaneously. There are different types of performance testing:

• Stress testing 
• Scalability testing 
• Endurance testing 
• Capacity testing 
• Responsiveness testing 
• Spike testing 
• Volume testing 

The performance testing offers several benefits like,

• It verifies the fundamental features to perform error-free 
• It allows early feedback for system performance 
• It optimizes the user experience 
• It identifies the bottlenecks and fixes them 
• It maximizes the resource utility 

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The difference between Performance and Load testing are: 

The acronym RACI stands for

• Responsible: The person or group who "owns" the work. Individuals are tasked with carrying out the activity to complete the task and are accountable for finishing the task or carrying out the choice. Multiple individuals can share responsibility. 
• Accountable: the person responsible for thoroughly completing the assignment and its owner. This individual, frequently the project executive or Sponsor, must exist. 
• Consulted: They are not directly involved in the process but provide the inputs when needed. 
• Informed: Stakeholders who need updates on tasks or choices but do not necessarily need to be formally consulted or personally contribute. 

Steps to create the RACI model:

1. List each task necessary to complete the project on the left side of the flowchart in a complete sequence. 
2. Understand all project roles and list them at the top of the chart. 
3. Fill in all the cells to identify the roles and accountability persons share in each task. 
4. There shouldn't be more than one position responsible for every task. If there are multiple conflicts regarding one task, resolve them all. 
5. In the final step, share, and discuss the RACI matrix with stakeholders and be on the same page before the project starts. 

Nominal Group Technique is a decision-making tool used in a group to help in decision-making, problem-solving, and giving solutions. Each group member gives their perspective on the situation using this way. The remaining answers are then sorted in order of preference by vote after any duplicates have been removed. The choice to proceed with is then determined to be the most popular option. 

When to use NGT?

NGT (Nominal Group Technique) approach helps to overcome specific issues that come up with teams, like; 

• When the team members are shy to share their ideas 
• When team members believe that their opinions are not being heard 
• When there is a conflict to discuss 
• Best tactics to introduce new team members 

Businesses employ a set of technologies called Six Sigma to control quality and enhance processes. By monitoring activities and analyzing the data and statistics gathered, the Six Sigma method is frequently used to eliminate flaws and optimize operations. 

The term "statistical process control" (SPC) applies to statistical process or production control methods. You may track process behavior, identify internal systems, and resolve production-related problems using SPC tools and methods. Statistical quality control and process control are often employed interchangeably (SQC). 

To use SPC intelligently, keep a few things in mind, 

1. Don't measure many variables; choose only primary focus points. 
2. SPC is an essential tool in Six Sigma; educate the team beforehand and engage in the process. 
3. Make SPC employees friendly. 

Pros:  

1. With the use of SPC, you may determine which variations are caused by a common factor and do not require special attention, allowing you to focus on improving the correct elements first. 
2. As the control chart is produced in real-time, feedback is instantaneous, and the variation will instantly be classified as standard or particular cause variation. 
3. Reduced process variances can be achieved without guesswork or haphazard modifications thanks to this instant responsive input. 

Cons:  

1. Putting SPC in place can be costly because, in most circumstances, a professional must be hired to train everyone on the charting techniques. 
2. SPC requires employee collaboration to function, which can occasionally be a constraint because using it might be perceived as an additional responsibility by employees. 

A mathematical diagram known as a scatter plot, a scatter chart, or scatter graph, displays values for two variables for a set of data and makes predictions based on the data. It comprises a set of dots, an X-axis (the horizontal axis), and a Y-axis (the vertical axis). The location of each dot corresponds to its unique X and Y axis values. It's a fantastic tool that can display nonlinear interactions between variables and is frequently employed in six sigma programs. 

Scatter Plot Correlation Analysis: 

A Scatter diagram is an essential analyzing tool for problem-solving in Six Sigma. Scatter plots are frequently used to display the relationships between the variables, known as correlation. There are three types of correlation: 

• Positive Correlation: A relationship in which two variables' values rise or fall together is a positive correlation. Similar to the last example, the y value increases as the x value does. 
• Negative Correlation: When two variables have a negative correlation, it signifies that they are inversely related; when one variable falls, the other rises, and vice versa. 
• No Correlation: No relation between the variables.

A staple in six sigma technical interview questions and answers, be prepared to answer this one using your hands-on experience.

The probability value, or P-value in Six Sigma, establishes the importance of outcomes based on the null hypothesis. According to the null hypothesis, the assertion that one attempt to show did not occur claims that the event's cause was not established. P-value falls between 0 and 1, and if the p-value is: 

• Less than 0.5- According to statistics, the event is essential because it has a significant value versus the null hypothesis. 
• Less than 0.05- According to statistics, the event has a substantial value for the null hypothesis; hence alternative hypothesis gets rejected. 

Properties of P-value: 

1. It's easy to calculate. 
2. It's easy to understand. 
3. It has simple and universal properties. 
4. It is reproducible. 

Effect size tells the difference between the group or defines the relationship between two variables and demonstrates the relevance of research finding in the real world. A significant or large effect size denotes the practical significance of a research conclusion, whereas a small impact size suggests limited practical implications. 

Why does Effect Size Matter? 

While statistical significance demonstrates the existence of an effect in a study, practical significance indicates that the impact is significant enough to have real-world implications. Therefore, P-values are used to indicate statistical significance, whereas effect sizes are used to indicate practical relevance. 

Because the sample size impacts it, statistical significance alone might be deceptive. No matter how tiny the effect is in reality, increasing the sample size always increases the chance of finding a statistically significant result. 

Contrarily, effect sizes are not affected by the number of samples. Effect sizes are only calculated using the data. 

Six Sigma brings positive changes to the organization and benefits the business in many ways; 

1. Aware decision-making: Six Sigma methodology is based on statistical data, which empowers one to make an objective decision and execute the best solutions. Six Sigma attempts to prepare you to handle your production or performance projects better by providing quantitative data to support them. 
2. Enhance good communication in the team: Six Sigma methodology encourage all team members to speak out about the issues and their problems, and this enables good communication between cross-functional team. 
3. Improve customer satisfaction: Six Sigma's primary goal is to reduce defects and bring necessary changes to products and services to meet customer satisfaction. 
4. Cost friendly: High costs result from poor quality and process inefficiencies, including missed deadlines, diminished customer loyalty, design changes, managerial changes, engineering changes, and so on. Whether as a result of inadequate planning or to address errors as they happen, they mount up. With organized expert teams, thorough process reviews, and close attention to data, Six Sigma employs a relentless method of eliminating those. 
5. Time Management: With better team structure, project planning, data collection and analysis, and business strategy, the entire organization will be more efficient.

A staple in senior lean six sigma interview questions with answers, be prepared to answer this one using your hands-on experience. This is also one of the top interview questions on lean six sigma.

There are five classical lean Six Sigma project types, 

1. Quick Win: It is also known as "just-do-it." The root cause of the issues is mostly department cantered, well-known, and easy to fix. 
2. Process Improvement: It is also known as DMAIC or PDCA. In this project, the cause is unknown, and there is an incremental reduction in defects and cost. 
3. Process Design: It is also known as DMADV. This includes creating a brand-new process. 
4. Process Redesign: Reengineering is called incremental improvements that don't satisfy customer needs. 
5. Infrastructure Implementation: It is also called process management, as it involves setting key measurement systems. 

By examining variation and its causes, a control chart can be used to monitor, regulate, and enhance process performance over time. Control charts focus on detecting and tracking the process variation. It allows keeping an eye on patterns over time, including variations and quantity, and identifies the events that interrupt the regular operation.

It keeps track of the development, aids in continuous learning, quantifies the process's capacity, and assesses any unusual circumstances that may be present. Usually, it is an element of the process management diagram. 

There are two types of control charts: 

1. Variable charts: These graphs show how measurements like height, weight, length, and concentration can vary. There are three types of variable charts, 

• Xbar-R chart 
• IX-MR chart 
• Xbar-S chart 

2. Attribute charts: These graphs show the information on defects and defectives. There are four types of Attribute charts, 

• P chart 
• NP chart 
• C chart 
• U chart 

It's a Six Sigma tool that prioritizes product or service features based on customer perception. When considering whether or not to invest time and money into a particular attribute, product development teams can consider three factors: basic needs, Performance, and fun. 

Business owners should use it to prioritize what customers need. Managers can use Kano Models to assess whether a product or service is helpful, satisfying, or exciting to customers. 

The Kano Model groups the critical aspects of developing or enhancing a good or service. A development team can classify features into the following categories to decide which to include and exclude. 

1. Mandatory features: These features are a must in this listed category. In other words, the customer will be completely dissatisfied if a good product or service doesn't have these. 
2. Performance: Businesses need to note and implement these features as extensions to customers' fundamental elements. There may be some unhappiness if they cannot be met, but it is not a deal-breaker. However, if they are met, the results will be much more satisfying. Moreover, they will give your product or service a competitive advantage. 
3. Excitement: These characteristics make the product or service more appealing to your target market. Even if they are not met, there won't be any client unhappiness. Instead, they are there to give you an even more significant competitive advantage. 
4. Indifferent: These characteristics significantly impact whether or not a client is satisfied, regardless of whether they are present. Determining whether or not the features satisfy the customer's needs may be challenging. 
5. Reverse: The buyer will be utterly unhappy if these traits are present. Customers won't buy your products or services if you don't include these components; they might choose your competitors instead. Likewise, their absence does not bring any satisfaction. 

The spaghetti diagram is one of the lean tools used to eliminate waste. It reduces transportation, motion, and waiting time wastes. The system tracks the movement of items such as products, papers, and people. The flow of items/people is visually represented along with distances and waiting times. There are several benefits to using a spaghetti diagram: 

1. Highlights the work layouts 
2. Highlight transport waste 
3. Reduce items with no values 
4. Adds value to the lean six sigma concept 

SIPOC provides a summary of the complete procedure and the next steps. It has several advantages and makes it simple to identify initiatives for process improvement before work is done. It aids in the smooth flow of projects that cannot be effectively scoped because of ill-defined or unclear metrics. It also aids in removing the following ambiguities: 

1. Who provides the inputs for process improvement?
2. Do you understand the requirements imposed on the inputs?
3. Who are your prospective clients concerning these procedures?
4. What are the customer's precise requirements?

There are five ways to use SIPOC:

• To visualize, comprehend, and convey high-level processes, SIPOC is used to see all functions from a single point of view. 
• Identify the customer needs. 
• Plan a process walk 
• Manage the thorough process mappings and choose the appropriate actions. 
• Understanding how suppliers, inputs, and process steps affect customers' wants is also beneficial. 

A kaizen event, sometimes known as a kaizen blitz, is a focused improvement initiative that can produce significant advancements in a brief period. The most typical duration of such an event is five days, but there is no particular significance to conducting a kaizen event that lasts five days. Delivering a quick breakthrough improvement is the aim. Kaizen activities must have a precise goal, immediate access to resources, and fast outcomes. 

Kaizen event has ten steps: 

1. Identify the issue 
2. Mapped with current scenario 
3. Visualized the desired scenario 
4. Set achievable goal 
5. Brainstorm all possible solutions 
6. Lay down the kaizen plan 
7. Execute the plan 
8. Analyze, record, and compare the plans 
9. Prepare summary 
10. Create an action plan 

This, along with other six sigma questions for freshers, is a regular feature in six sigma interviews, be ready to tackle it with the approach mentioned below.

The Zero Defects concept, pioneered by Philip Crosby, emphasizes doing things right first and reducing defects and errors in a process. The ultimate goal will be to eliminate all flaws. Nevertheless, it may not be possible in practice, so the best we can do is to ensure that errors or defects are as rare as possible. Maximizing profitability is the ultimate goal of achieving zero defects.

Pros:  

1. Cost savings are brought on by less waste. However, this waste may include squandered materials and time due to needless rework. 
2. Cost savings since time is now solely spent on manufacturing items or services created according to consumer demands. 
3. Creating and delivering a final product that consistently complies with customer needs will increase customer happiness, customer retention, and profitability. 
4. It is possible to calculate the quality cost 

Cons:  

1. Difficult to achieve 
2. It sounds abstract to the listener 
3. Time bounded approach 

Lean Six Sigma emphasizes defect prevention over defect detection in a fact-based, data-driven approach to improvement. Creating a competitive advantage reduces variation, waste, and cycle time while promoting standardization and flow. The advantage of lean six Sigma are: 

• Measurement of the co Businesses may enhance the work experience for employees and the customer experience by making essential procedures more efficient. In addition, both inside and outside of a corporation, this can increase loyalty. 
• Streamlined and made simpler processes can provide an organization with more Control and make it easier to seize new possibilities. 
• They may also result in increased income and sales, decreased expenses, and better company outcomes. 
• Participating in a team project or company-wide efficiency drive can help employees develop new skills, including project management and analytical thinking, increase their career advancement possibilities, and foster camaraderie. 
• Participating in a team project or company-wide efficiency drive can help employees develop new skills (including project management and analytical thinking), increase their career advancement possibilities, and foster camaraderie. 

Measurement System Analysis, or MSA, is a formal statistical study that analyzes whether the measurement system used can provide reliable data so that you may make the best possible data-driven decisions. 

The fundamental elements of a Measurement System Analysis are; 

1. Repeatability: The difference between subsequent measurements of the same component or characteristic taken by the same individual using the same gauge is known as repeatability. 
2. Reproducibility: When measuring the same feature on the same part, reproducibility is the difference in the average of measurements made by various people using the same instrument. 
3. Stability: If the variation of the measurement system remains constant across time, it is said to be stable. 
4. Bias: The bias is the deviation from the actual or reference value in the observed average measurement. The same part must be measured numerous times to determine the average measurement before measuring the bias. 
5. Linearity: The difference in the bias value over the measurement tool's typical operating range is known as linearity. In other words, it is the variation in bias over the measurement equipment's operational range.