Lean Six Sigma Black Belt - General Terms and Notes SixSigmaStudyGuide

The 3 G Of Kaizen

#1: Gemba - The Shop Floor #2: Gembutsu - The Actual Product #3: Genjitsu - The Facts

Advantages of using a histogram?

* It helps to visualize the distribution of the data Summarize the large data set graphically * It helps to make a future prediction based on data * Assists in decision making * Simple to understand and also easy to communicate with the team

Disadvantages of using a histogram?

* It uses only continuous data * More difficult to compare two data sets * Difficult to read values because data is grouped into data sets

Correlation

A relationship between two events. They occurred at much the same time, in the same population, or in the same circumstances. For example, spilling a glass of milk and dropping an egg. They might occur at the same time, and they might have the same cause - clumsiness or a fright. But one would rarely cause the other to happen.

A sample is described by

A sample is described by statistics (e.g. xBbar, s).

Multi-Vari Chart

A simple way to measure process variation and to compare several processes at once. The range is depicted by a vertical line and the mean by a short horizontal line placed on the vertical line

68-95-99.7 rule

An empirical rule used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of one, two, and three standard deviations respectively.

Just-In-Time

An inventory-management approach in which supplies arrive just when needed for production or resale

A Pareto Diagram ranks categories in ascending order. (T/F)

F = The ranking of a Pareto Diagram is in descending, not ascending order.

Common cause variation

Happens in standard operating conditions. Fluctuations might occur due to: temperature humidity metal quality machine wear and tear. Common cause variation has a trend that you can chart. In the factory mentioned before, product differences might be caused by air humidity. You can chart those differences over time. Then you can compare that chart to weather bureau humidity data.

The main objective for companies to implement Six Sigma is to?

Increase profit. At the end of the day, Six Sigma is about increasing profit. Objectives like waste reduction, quality improvement, etc. result in savings and ultimately more profit.

Variation Source: Piece to piece

Piece to piece: variations that occur between different instances of the same product. Also known as cyclical variation.

Project Charter provides clarity by:

Provides clarity by: Ensuring the project leads understands the sponsor's requirements Provides key information needed to get started Provides a reference document Defines success of the project.

The House of Quality is a primary tool for?

Quality Function Deployment (QFD) uses the House of Quality (a relationship matrix that transforms the Voice of the Customer to design requirements and performance targets)

What is variation?

Quick answer: It's a lack of consistency. The differences between multiple instances of a single product variation.

How to Analyze a Histrogram

Six Sigma practitioners can use the pattern reflected in the histogram to discern a process variation. It is a graph of a frequency distribution in which the class interval plotted on X- axis and their respective frequencies on the Y- axis. It is a two-dimensional diagram. The width of each bar indicates the interval size. The height of each bar indicates the frequency of the interval. There are no gaps between adjacent bars Continues nature of quantitate data Height or length of each rectangle shows the frequency of the class, and breadth indicates size of class interval. Therefore, the total area covered by histogram represents total frequencies.

DMAIC: Measure Phase

The second phase of the DMAIC process. Determine how the process is performing currently in an unaltered state. During this phase, you will: Identify the data that you need to collect. Decide what measurements to use. Figure out what methods to use to collect your measurements. Determine the level of variation that you'll be dealing with. Collect the data as per previous points.

Six Sigma focuses on

1. Change empowerment 2. Seamless training of resources 3. Consistent top management support

Two types of variation

1. Common cause 2. Special cause.

7 Six Sigma Tools

1. DMAIC 2. 5S 3. Seven Wastes 4. Value Stream Map 5. Process Mapping 6. Voice of Customer (VOC) 7. Kaizen

Six Sigma methodologies

1. DMAIC (Define, Measure, Analyze, Improve, Control) 2. DMADV (Define, Measure, Analyze, Design, Verify)

Six sigma aims to reduce

1. Time 2. Defects 3. Variability

The mean of normally distributed data is 6. What is the mode?

6 - Normally distributed data means that mean = mode = median. (Good trick question)

Control limits of a Control Chart are?

=3 and -3 siControl Limits represent the range of expected variation which is ±3 standard deviations off the average.

Heijunka

A Japanese term for production leveling or production smoothing. Heijunka is a Lean method for reducing the unevenness in a production process and minimizing the chance of overburden

Mura

A Japanese word for unevenness or inequality, which is a form of waste.

What is a Histogram

A bar graph that shows the frequency data occur within a certain interval. In other words, it is a bar chart showing the frequency of an outcome. In Six Sigma, we can use a histogram to visualize what is going on. It can reflect the voice of the process. A Histogram is a popular statistical method of presenting continuous series or class interval frequency distributions. A histogram is never drawn for a discrete variable or data.

Causation

A causative relationship between two events; one caused the other to happen. For example, dropping an egg could cause it to land on the floor. These will also happen at almost the same time, by human observation. But unlike the milk-and-egg example, one - dropping an egg - can be shown to directly cause the other - it landing on the floor.

Flowchart

A diagram that represents a workflow or process.

What is Six Sigma

A framework to make an organization more competitive by focusing on being effective and efficient. It is a systematic problem-solving approach that is centered around defect elimination and variation reduction which leads to process improvement. Six Standard Deviations A Six Sigma process has a specification limit that is 6 times its sigma (standard deviation) away from its mean. The 6 refers to the ability to fit the good outputs of the process to fit within 6 standard deviations (or sigmas). Another way to say it is that only 3.4 defects per every million opportunities fall outside the specification limits that we've set at 6 sigmas away from center. You can also think of it as a level of excellence that can be quantified and easily compared against other processes. If you only get 3.4 defects per million out of your process, i.e. a 99.9999998% success rate, you have a 6 sigma process.

Why use a histogram?

A histogram is one of the 7QC tools that is typically used to assess process behavior and demonstrate if the data follow a normal distribution. The purpose of a histogram is to graphically summarize the distribution of a univariate data set. It graphically shows the centre, spread, skewness of the data, presence of outliers, and also presence of multiple modes in the data. While a normal histogram just tells you the data, a well-constructed histogram tells you more than just the raw data. A normal histogram helps to understand whether the data is normally distributed, dispersion and central tendency of the data. In contrast, a well-constructed histogram helps to visualize the VOC, and also you could even include the specification limits to reflect customer expectations.

When to use a histogram?

A histogram is used when the data is numerical and continuous. Histograms are used to view the overall distributional features and peaks of the distribution in the data set. Furthermore, it can be used to identify whether the distribution is skewed or symmetric and the outliers. It helps to analyze whether the process meets customer requirements and also to identify the process changes over time.

Standard Deviation (SD)

A measure of variability that indicates the average difference between the scores and their mean. The average distance from a central location you expect to observe. Six SDs means we are measuring six standard deviations from something to something. Six sigma requires that the process operate so that the nearest requirement is at least six standard deviations from the process mean. A great way to illustrate the SD of a process is a histogram. Rule of order of operations. Do what's in the parenthsis first. The x represents the individual values or data points the x bar represents the average or mean of the individual data points. Then square the data points. The capital sigma that looks kind of like an E is instructing us to sum up the individual squared results. Now we divide that result by the number of data points (n)

Lean

A methodology that aims to remove any part of a process that does not bring value to the customer. Doing more with less while doing it better. Continous pursuit of waste elimination. The philosophy behind it comes from the Japanese manufacturing industry by Bob Hartman who at the time was part of Toyota.

Lean Six Sigma

A methodology that combines the organizational elements and tools of Six Sigma with Lean's focus on waste reduction. 1. Eliminating problems 2. Removing inefficiencies and waste 3. Improve the working conditions 4. Customer's needs are better satisfied.

A population is described by

A population is described by parameters (e.g. μ and σ).

Six sigma level is

A statistic used to describe the performance of a process relative to the specification limits. Defect-free product 99.9996% of the time allowing only 3.4 defects per million opportunities. The number of Standard Deviations from the Mean to the closest specification limit of the process.

Causal Theory

A theory about what causes a problem and how particular responses would alleviate that problem. In Six Sigma terms, means that you create output (y) from an input (x) and a function (f). It's made up of three components: y: What you get out of a process. In a manufacturing context, this is a physical product. x: What you put into a process. In the same manufacturing context, this is a material or part. f: What you do to turn x into y. In manufacturing, this is a machining or assembly procedure. y = f(x) Output = method * input When you have a problem with your output (y), causal theory tells you that there are two possible culprits: f: Your procedure for creating that output. x: The materials or information you're adding to that procedure.

Process Map

A tool that graphically shows the inputs, actions and outputs of a process in a clear, step-by-step map of the process. Measure Phase

SIPOC Diagram

A tool that helps document a high level process from the suppliers to customers. Measure Phase

When is a Z test used?

A z-test is used for Hypothesis Tests of the mean if the standard deviation of the population is known. A z-test is a statistical test used to determine whether two population means are different when the variances are known and the sample size is large.

DMADV (Creating new product or service from scratch (Analyze Phase)

Analyze the product to determine if there are better ways to achieve the desired results. Areas of improvement are determined and tested.

DMADV (Creating new product or service from scratch (Design Phase)

Based on learnings from the analysis phase, the new product or process is designed. The analysis phase is repeated based on the new design. You also put together a focus group and see how they receive it. Based on their feedback, changes are made.

Six Sigma coined by

Bill Smith. He was an American engineer and also known as father of Six Sigma. It was first implemented at Motorola in the year 1986 as a general approach to measuring quality in business performance terms. Further, it became popular management approach at GE with Jack Welch in early 1990s'.

Critical To Quality (CTQ) Trees

CTQ Trees break down customer needs (e.g. I want good tea) into drivers (e.g. taste, temperature, cost) and from there into requirements (e.g. rich and non-acidic taste, temperature between 160 - 185 °F, price between $1.50 and $2.50).

Voice of the Customer (VOC)

Customer descriptions for functions and features customers desire for goods and services. Data that represents the needs and wants of your customers.

Three Key Elements of Six Sigma

Customers: Customers are the key for business and they are the top priority. Customers defines the quality requirements and also expect on-time delivery, high performance, great service and many more. However, meeting customer requirements is not sufficient in this competitive world. Process: Defining the process and corresponding metrics is the key aspect of Six Sigma. Since the customer is key for any business, Quality needs to be looked at from customer's perspective. This helps to identify the gaps in processes and the work necessary to improve them. Employee: Without leadership commitment, it is difficult to implement Six Sigma in any organization. The organization must involve all employees with well-defined roles and clear objectives. Furthermore, organizations need to provide required resources like people, training, budget, and more.

Three Key Elements of Six Sigma

Customers: they define the quality requirements and expect on time delivery. Process: Quality needs to be looked at from the customer's perspective to help identify gaps in processes and the work necessary to improve them. Employee: The org must involve all employees with well-0defined roles and clear objectives. Orgs also need to provide the required resources like people, training, budget, and more.

What is DMAIC? Quick Answer

DMAIC is Six Sigma's signature framework for process improvement. It provides a structured way of improving a process.

How to Find and Reduce Hidden Causes of Variation

DMAIC methodology is the Six Sigma standard on how to identify variation in a process, analyze the root cause, prioritize the most advantageous way to remove a given variation, and test the fix. The tools you would use depend on the kind of variation and the situation. Typically we see either a "data door" or a "process door" and use techniques that are most appropriate. For a smaller, shorter cycle methodology you could try Lean tools like Kaizen or GE's Work Out.

DMADV (Creating new product or service from scratch (Define Phase)

Define requirements from customers based on inputs from customers, historical data, and industry research. You determine what is needed to become a success.

DOE

Design of experiments

How do you counter special cause variation?

Exigency plans. These are extra or replacement processes. We only use them if the special cause is present, though. (A large change in metal quality is unusual. So we don't want to change any of our manufacture processes. Instead, we implement a random check of quality after every shipment. Then, an extra process to follow if a shipment fails its quality check. The new process involves requesting a new shipment. These changes don't lengthen the manufacture process. They do add occasional extra work. But extra work happens only if the cause is present. Then, the extra process eliminates the cause.)

Two ways to determine the result of a Hypothesis Test.

Firstly, by comparing z and zc (test type needs to be considered, e.g. left-tail, two-tail, or right-tail). Secondly, by comparing the p-value to alpha (same rules for all test types).

Difference between frequency distributions and Histogram

Frequency distributions organize raw data or observations and represents data with x's or check marks, whereas histogram is a continuous relative frequency graph. It is a bar graph version of a frequency diagram.

Multi-Vari Studies

Graphically display patterns of variation. Identify all possible X's. Used to identify possible x's or families of variation.

Kaizen

Kaizen means improvement on a continuous basis. Originated in Japan, Kai means change and zen means for good. As per the concept and philosophy of Kaizen, everything can be improved. Applying this philosophy in operations helps to improve and increase the efficiency of different processes in an organization.

How do you counter common variation?

Long term process changes.

DMAIC: Control Phase

Make regular adjustments to control new processes and future performance. Once you're happy that the chosen solution will improve the process, it's time to implement the Control phase. This is where you actually implement said solution, but there are some other tasks too: Document the solution. Collect data about how the solution is working in production. Put supports in place to ensure that the solution is permanent, not temporary. Set up a plan to deal with any issues that might arise. Plan handover to the operations personnel.

Waste or defects

Measurable product characteristics that do not meet a customer's requirements (i.e. defective products). In other words, any process performance outside of defined specification is considered waste or a defect.

Six elements in any process? The 6 Ms of Six Sigma

Method Mother Nature, or Environmental Man, or People Measurement Machine Materials.

Muda

Muda is the Japanese word for waste. There are different forms of waste including waiting, inventory, transport, and motion.

Multi-vari charts

Multi-vari charts are useful in visualizing 2-way interactions. * Help you understand within piece, piece-piece and time-time variation. * These variations are also known as Positional Variation, Cyclical Variation, and Temporal Variation. Within Unit or Positional Between unit or cyclical Temporal or over time shift to shift (day to day / week to week) * With the help of multi-vari charts you can clearly identify what is the major source of variation in your process. * This variation family has roots in common and special causes of variation, so Black belts need not worry about dealing with a new family of variation. * MVA helps your identify the dominant source of variation. Remember for a multi-variable analysis to work the output must be continuos and the sources of variation discrete.

Special cause variation

Occurs in nonstandard operating conditions. Disparities could occur if: a substandard metal was delivered. one of the machines broke down. a worker forgot the process and made a lot of unusual mistakes. This type of variation does not have a trend that can be charted. Imagine a supplier delivers a substandard material once in a three-month period. Subsequently, you won't see a trend in a chart. Instead, you'll see a departure from a trend.

What makes a good project?

One there is an obvious link to the strategy of the business. Will have reach benefits and bang for the buck. Needs clear sponsor and also needs to be time bound. Keep it between 1 and 6 months.

Seven Wastes

Overproduction, queues, transportation, inventory, motion, overprocessing, defective product. Seven Wastes are looked as blockage against the productivity.

Kano Model

Prioritization approach. An approach to prioritizing features on a product roadmap based on the degree to which they are likely to satisfy customers. A technique that categorizes customer requirements into three types: 1. Delighters, 2. Satisfiers, 3. Dissatisfiers. The Kano Model incorporates five categories: basic, performance/satisfiers, excitement/delighters, indifferent attributes, reverse attributes. Each of these has its own degree of importance to users. A product that lacks certain basic features could suffer from reduced functionality and irritate users.

Upper specification limit, or USL

Represents the highest limit that a measurement or reading can reach and still be acceptable to the customer.

Lower specification limit, or LSL

Represents the lowest limit that a measurement or reading can reach and still be acceptable to the customer.

RPN

Risk Priority Number: The value that will be used to rank order of concerns in FMEA RPN = (SEV)*(OCC)*(DET) Severity * Occurrence * Detection

The most important factor for successful Six Sigma projects

Senior management controls resources and sets the strategic direction of the company. Hence, their support is essential.

Where does the sigma come from?

Sigma denoted by symbol σ (a Greek letter) represents the standard deviation of a population. Primarily it characterizes the dispersion (or 'spread') of a set of data values with respect to mean. A standard deviation is a value you have to calculate and is dependent on the data your process generates.

Where did Six Sigma begin?

Six Sigma was originally developed by Motorola - first by Bill Smith, then Mikel Harry as a general approach to measuring quality in business performance terms. Over the years, especially in the 1990s continuous improvement tools and methods were developed by Deming, Juran, Shewhart, Ishikawa, Shingo and Taguchi. Now it has evolved be a project driven approach to process improvement that follows the five-step process known as the DMAIC cycle. This process has been used by the world's best companies to save and make billions of dollars.

When should the DMAIC process not be used?

Some projects aren't suitable for this process. For example: It's already very clear what the problem is, and how to solve it. There's no or little available data on the process to be improved. Managers and leaders do not support improvements to this process. The process does not directly impact key performance indicators. Measuring process improvements would be difficult or impossible.

5S

Sort, set in order, shine, standardize, and sustain. To organize equipment, resulting in an orderly workplace. AKA lean technique. 5S Workplace Organization is A visual system. Also a Kaizen event. 5S derives its name from five Japanese terms beginning with the "s" utilized to create a workplace suited for visual control and lean production. Collectively, the 5S's detail how to create a workplace that is visibly organized, free of clutter, neatly arranged, and sparkling clean. The 5S system is often a starting place for implementing lean operations

Phases of team development

The Tuckman Model describes 4 stages of group development: Forming, Storming, Norming, and Performing.

Six Sigma's Basic Premises

The basic purpose of six sigma is to delight the customers; this can be achieved by delivering the quality product. Hence it is fundamentally focuses on variation reduction and waste elimination. This leads to increased efficiency.

DMAIC Define Phase

The first phase of the DMAIC method which involves defining the problem or opportunity, determining the voice of the customer/customer requirements, and outlining the project purpose/scope. Two tools used: Charter and SIPOC Diagram (Suppliers, Input/Input Reqs, Process, Output reqs/Output and Customers) In the Define phase, you collate a lot of information that you already have available. You'll: Understand the project, including its purpose and scope. Map the current process. Determine whether the process is a good candidate for DMAIC. Detail customer expectations. Estimate timelines and costs.

DMAIC: Improve Phase

The fourth phase of the DMAIC process focuses on identifying opportunities and implementing solutions. Make changes. You've identified the root cause of your issue in the Analyze phase. Now you need to come up with a solution. You'll: Pull in people who perform or oversee the process. Brainstorm potential solutions. Determine criteria for selecting a solution. Weigh potential solutions against the criteria. Pick a solution. Test the chosen solution. Measure the results and compare them to the Measure phase data.

Variation

The range of difference between the statistical mean and all data points that are used to calculate the mean. In other words, the extent to which process performance varies around the mean.

Where does the six come from?

The six refers to how many standard deviations away from the mean we set the specification limits in a 6 sigma process.

Critical to Quality (CTQ)

The specific, measurable characteristics of a product or service that customers say are necessary for their satisfaction. (i.e. check-in speed, wifi speed, jacuzzi, cable TV).

DMAIC: Analyze Phase

The third phase of the DMAIC process focuses on identifying the root cause (or causes) of a process problem. In the Analyze phase, you work with the data that you collected in the Measure phase. You'll: Identify defect causes. Analyze these to pinpoint the root cause.

Lead Time

Time between order and delivery to customer

Takt Time

Time to meet customer demand. Takt time is the rate at which you need to complete a product to meet customer demand. For example, if you receive a new product order every 4 hours, your team needs to finish a product in 4 hours or less to meet demand.

Cycle Time

Time to produce one unit Time required for the product or transaction to go through the entire process beginning to end.

Variation Source: Time to time

Time to time: variations that occur at different production times. Also known as temporal variation.

Control Limits are too wide if subgroup sizes are?

Too Small. Control Limits get more narrow as subgroup sizes increase. The larger the subgroup size, the closer the control limits to the mean of the process.

What tools can be used to identify common cause variation?

Use run charts to look for common cause variation. Mark your median measurement. Chart the measurements from your process over time. Identify runs. These are consecutive data points that don't cross the median marked earlier. They show common cause variation.

DMADV (Creating new product or service from scratch (Measure Phase)

Use the customers requirements to create the specification. The specification helps to define the product in a measurable method so that data can be collected and compared with specific requirements.

VSM

Value Stream Mapping. Provides a visual representation of the flow of materials and information throughout the organization. It helps to identify, demonstrate, reduce waste and finally create effective flow through all the processes in the manufacturing organization. Measure Phase

Calculating variation

Variation is the square of a sample's standard deviation. Variation = SD squared

VOC

Voice of Customer (VOC) Organizations to understand the needs and expectations of the external customers to well design the product and services. Customers will weigh the value of a product based on the cost, quality, availability, and features. Reactive: Complaint logs, Hotlines, Tech support calls, Website activity Proactive: Focus Groups, Interviews, Surveys, Comment cards, Marketing research, Observation: "Go to the Gemba"

Why measure variation?

We measure it for a couple of reasons: Reliability: We want our customers to know that they'll always get a certain level of quality from us. Also, we'll often have a Service Level Agreement or similar in place. Consequently, every product needs to fit specific parameters. Costs: Variation costs money. So to lower costs, we need to keep levels low.

Variation Source: Within Piece

Within piece: variations within a single instance of a product. Also known as positional variation.

When is the Xbar-S Chart used?

Xbar-S charts are used for continuous data with subgroup sizes larger than 9.

DMADV (Creating new product or service from scratch (Verify Phase)

You check whether the end result meets or exceeds the customers requirements and expectations.

correlation coefficient

a statistical measure of the extent to which two factors vary together, and thus of how well either factor predicts the other Correlaion coefficient always assumes a value between -1 and +1.

What tools can be used to identify special cause variation?

use control charts to look for special cause variation. Mark your average measurement. Mark your control limits. These are 3 standard deviations above and below the average. Identify data points that fall outside the limits marked earlier. In other words, above the upper control limit or below the lower control limit. These show special cause variation.

A sample of 224 items has been selected from a population with a mean 80 and a standard deviation of 5.2. What is the z value that the sample has a mean 73?

z = (x - μ) / σ = (73 - 80) / 5.2 = -1.34615 which is a probability of 0.0885