Term
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Definition
| Six Sigma is about applying a structured, scientific method to improve any aspect of a business, organizaiton, or process. It's about engaging in disciplined data collection and analysis to determine the best possible ways of meeting your customer's needs while satisfying yours. Primarily, it's a program designed to reduce process variation. |
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Term
| What is Six Sigma's role in the organization? |
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Definition
| Six Sigma's role is to help management produce the maximum value, while using minimum resources. It applies scientific principles to processes and products. By using the DMAIC (Define, Measure, Analyze, Improve, Control) approach processes or products are improved in the sense that they are more effective, more efficient, or both. |
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Term
| How is Design for Six Sigma (DFSS) used? |
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Definition
| If no process or product exists, or if existing processes or products are deemed beyond repair, then design for Six Sigma (DFSS) methods are used to create effective and efficient processes or products. Designing for Six Sigma includes eliminating sources of error. |
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Term
| What is involved in the Define phase of the DMAIC process? |
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Definition
Project charter
VOC tools (surveys, focus groups, letters, comment cards)
Process map
QFD, SIPOC
Benchmarking |
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Term
| What is involved in the Measure phase of the DMAIC process? |
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Definition
Measurement system analysis
Exploratory data analysis
Descriptive statistics
Data mining
Run charts
Pareto analysis |
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Term
| What is involved in the Analyze phase of the DMAIC process? |
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Definition
Identify the root causes of defects, defectives or significant measurement deviations whether in or out of specifications (the "X"s, independent variables)......Cause-and-effect diagrams....
Tree diagrams....
Brainstorming....
Process behavior charts (SPC)....
Process maps....
Design of Experiments....
Enumerative statistics (hypothesis testing)....
Inferential statistics (Xs and Ys)....
FMEA....
Simulation |
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Term
| What is involved in the Improve phase of the DMAIC process? |
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Definition
Reduce variablility or eliminate cause......Force field diagrams....
7M tools....
Project planning and management tools....
Prototype and pilot studies, |
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Term
| What is involved in the Contol phase of the DMAIC process? |
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Definition
With the desired improvements in place, monitor the process to sustain the improvments......SPC....
FMEA....
ISO 900x....
Change budgets.... bid models.... cost estimating models....
Reporting system |
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Term
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Definition
| Six Sigma is a highly disciplined process that focuses on developing and delivering near-perfect products and services consistently. Six Sigma is also a management strategy to use statistical tools and project work to achieve breakthrough profitability and quantum gains in quality. |
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Term
| In a normally distributed process, what percentage of measuremens will fall within +/- 3 sigma of the process mean? within +/-4.5 sigma? |
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Definition
| 99.73% of the measurements will fall within +/- 3 sigma and 99.99966% will fall within +/- 4.5 sigma. |
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Term
| Where does +/- 6 sigma come from and how many defects per million opportunities is it associated with? |
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Definition
| Motorola noted that many process operations tended to shift 1.5 sigma over time. A normally distributed process with normally distribution variation about the mean, would need to have specification limits of +/- 6 sigma in order to produce less than 3.4 defects per million opportunities. |
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Term
| What % of measurements from a normally distributed process are included within +/- 3 sigma boundaries? within +/- 4.5 sigma? |
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Definition
| 99.73% within +/-3 sigma and 99.99966% within +/-4.5 sigma. |
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Term
| Wat are the defect levels (PPM) associated with +/-1,2,3,4,5,6 sigma level boundaries? |
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Definition
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Term
| What business successes result from a Six Sigma initiative? |
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Definition
| Cost reductions....Market share growth....Defect reductions....Cultural changes....Productivity improvements....Customer relations improvements....Product and service improvements....Cycle-time reductions |
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Term
| Why does Six Sigma work (according to Snee 1999)? |
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Definition
| Bottom line results....Senior management buy in....DMAIC provides disciplined approach....Short project completition times (3 to 6 months)....Clearly defined measures of success....Infrastructure of trained individuals (black belts)....Customers and processes are the focus....With backbone of sound statistical approach |
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Term
| What does SIPOC stand for? |
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Definition
| Suppliers, Inputs, Process, Outputs, and Customers |
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Term
| Draw an Expanded SIPOC Model. |
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Definition
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Term
| What is the advantage of using a SIPOC model? |
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Definition
| Display a cross functional set of activities in a single, simple diagram.... create a big picture perspective to which additional detail can be added....Use the same framework for either large organizations or smaller processes (Pande 2000).......The ultimate goal is to identify essential work flows and sources of variation in work over time......SIPOC captures the key components of sucess from suppliers, through internal processes and on to key customers. |
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Term
| How do Black Belts typically function in an organization? |
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Definition
| In some organizations, BBs are full time positions that report directly to management sponsors, who, in turn, have specific projects for them. In other organizations, BBs continue in their normal assignments and participate in process improvement teams as needed. In this structure, BBs act as internal consultants and are pulled into teams when their specific skills are needed. |
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Term
| What are some of the considerations for developing a Six Sigma project? (Harry 2000) |
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Definition
| Fopcus on project cost savings....Focus on customer satisfaction deliverables....Focus on processes....Focus on problems....Focus on a targeted locations....Focus on design....Focus on supplier processes |
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Term
| What is the key to achieving Six Sigma improvements? |
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Definition
| The characterization, measurement, analysis, and control of variation is the central theme of Six Sigma. |
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Term
| What is common cause variation? |
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Definition
| Some variation is just natural; you can't eliminate it. This type of variaiton is called common cause variation. You can act to reduce common cause variaition, but you can't eliminate it. In coin tosses, the variaition in the number of heads from set to set is perfectly normal. |
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Term
| What is special cause variation? |
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Definition
| Special cause variation is directly caused by something special. With Six Sigma your effort is spent in identifying the difference between common cause variation and special cause variation. |
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Term
| Which type of variation (special or common cause) should a Six Sigma project concentrate on first? |
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Definition
| In general, it's best to work on reducing special-cause varation before trying to reduce common-cause variation. The reason is because when you have special-cause variation, the process is not stable or predictable, and you can't be sure of what's happening. |
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Term
| Assume a 1 on a die represents a defect. What is the probability of rolling 100 dice without a defect (i.e., without a 1)? |
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Definition
| (5/6)^100 = 0.000000012 probability or about 1 chance in 82,817,975 |
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Term
| How does Vilfredo Pareto's 80/20 rule apply to Six Sigma? |
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Definition
| 20 percent of a system's inputs accounts for 80 percent of the influence on that system. While a great number of factors are connected to a given outcome, only a few carry the weight to change that outcome in a significant way. In a process, a few key variables are the cause of most performance problems or defects. |
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Term
| What's at the heart of the Six Sigma process? |
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Definition
| Data-driven decision is an integral part of a Six Sigma program. |
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Term
| What do each of the DMAIC components contribute? |
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Definition
| Define the problem......Measure the extent of the problem.....Analyze the sources of variation......Improve the process.....Control the process for sustained improvement. |
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Term
| What is the acronym meaning of SWOT? |
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Definition
Strengths
Weaknesses
Opportunities
Threats |
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Term
| In SWOT analysis, what does the S stand for and mean? |
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Definition
S stands for strength. It's something the company is good at doing.
Examples: Engineering expertise, Technical patents, Skilled workforce, Solid financial position, Reputation for quality |
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Term
| In SWOT analysis, what does the W stand for and mean? |
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Definition
W stands for weaknesses. A weakness is something the firm lacks or is a condition that puts it at a disadvantage.
Examples: Poor cash flow, Outdated technology, High overhead expenses, Lack of access to skilled labor, Poor quality perception by customers |
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Term
Quality History Influencing Six Sigma
Philip B. Crosby (1928 - 2001) |
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Definition
While other quality deep thinkers could be viewed as aqcademicians, Crosby was considered a businessman. Crosby stated that corporate management must make the cost of quality a part of the financial system of the company.
Four absolutes of quality
Quality is conformance to requirements, and requirements are what the customer says they are.
Quality comes from prevention
The quality performance standard is zero defects.
Quality measurement is the proce of nonconformance.
Crosby also developed a 14-step approach to quality improvement. |
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Term
Quality History Influencing Six Sigma
Dr. W. Edwards Deming (1900 - 1993) |
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Definition
Developed the 14 Obligations of top management and the 7 deadly diseases that management must cure.
Some of the 14
Cease dependence upon inspection as a way to achieve quality.
End practice of awarding business based on price tag
Eliminate slogans/targets asking for increased productivity without providing methods |
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Term
| What was Deming's chain reaction with Japan in the summer of 1950? |
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Definition
| Improve quality --> Decrease cost (less rework, fewer delays)-->Productivity improves --> Capture market with better quality and price --> Stay in business --> Provide jobs |
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Term
Quality History Influencing Six Sigma
Dr. Armand V. Feigenbaum (1920 - ) |
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Definition
| Feigenbaum is given credit for establishing the concept of total quality control. TQC maintains that all areas of the company must be involved in the quality effort. |
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Term
An organized and disciplined approach to problem solving in most Six Sigma organizations is called:
a - SIPOC
b - DMAIC
c - PDCA
d - DPMO |
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Definition
| b - DMAIC (Define, Measure, Analyze, Improve, Control) |
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Term
Using Six Sigma methodology, a company at 4.5 sigma would have a failure rate of
a - 3.4 ppm
b - 233 ppm
c - 1350 ppm
d - 6210 ppm |
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Definition
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Term
| Just as the jury in a criminal trial, we are not infallible in our judgments. In spite of our best efforts, errors happen. What are these errors? There are two types: In a criminal court situation, we could convict an innocent man or acquit a criminal. |
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Definition
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Term
| Describe Type I and Type II errors. |
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Definition
| cause of the punishment involved, the first is considered by far the more serious of the two. There are also penalties in hypothesis testing. Hence, rejecting the null hypothesis when it is true is called 'Type I error' (the more serious error) and failing to reject the null hypothesis when the alternative is true is called 'Type II error' (the less serious error). |
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Term
| Describe Type I Error (alpha risk). |
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Definition
Type I Error (α)
In Hypothesis Testing, as in most judicial systems, Type I Error (convicting an innocent person) is considered the more serious of the two potential errors. The probability of this error is denoted by α (alpha) and is also known as the Significance Level of a test. Thus, alpha represents the amount of "risk" we're prepared to take in erroneously rejecting the null hypothesis. |
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Term
| Describe Type II Error (Beta risk). |
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Definition
Type II Error (β)
Type II error (not convicting a guilty person) is the "lesser" of the two errors and its probability is denoted by β (beta). Ideally, we would want to eliminate or at least minimize both forms of error to increase the chance of making the right decision (correct verdict). Unfortunately, it is not possible to minimize the two errors simultaneously since reducing one leads to an increase in the probability of the other. We try to overcome this problem by setting alpha (the more serious error) at a maximum acceptable level (the convention being 0.05, or 5%) and minimizing beta (the convention being 0.20, or 20%). |
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Term
| Sketch an example of a Type I error. |
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Definition
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Term
| Sketch an Example of Type II error. |
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Definition
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Term
| What is the power of a test? |
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Definition
| The Power of a test answers the question: If the null hypothesis is false, what is the probability that the data from the experiment will reject the null hypothesis? In other words, Power is the chance of finding a significant effect when one does exist. Naturally, a high-powered test is desirable. As you will see below, however, several factors are tied to the power of the test, and the goal of a Power Analysis is to strike a balance among these factors so as to achieve the most sensitive test given the available resources. |
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Term
| What are four factors that impact a test's power (or beta risk)? |
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Definition
Size of Effect
Significance level (apha risk)
Sample size
Population standard deviation |
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Term
| How does the effect size impact the Power or beta risk? |
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Definition
| The larger the size of the effect you're looking for, the better your chance of finding it. |
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Term
| How does the alpha risk level impact power? |
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Definition
| If avoiding a Type I error were the only concern, you would always fix alpha at a low level such as 0.01 or 0.05. But things are not so simple, because Type I and Type II errors are interdependent: as one decreases, the other increases. Since power is computed as (1-β), this means that power and alpha are directly related: for a given effect and sample size, as alpha increases, so does the power. Therefore, select alpha based on the study goals. For instance, if it is important not to overlook a potential effect, such as for a promising new drug compound, use a higher alpha, say 0.2. If on the other hand, the new drug carries the risk of serious side-effects, you might want to be stricter and use a low alpha level, say 0.01. |
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Term
| How does sample size affect the power or beta risk? |
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Definition
| Sample Size (n): The study sample must be sized appropriately in order to meet its goals. If the sample is too small, the test is likely to be inconclusive, even if an effect of practical importance does exist. On the other hand, an over-sized study uses more resources than necessary and may detect an effect that is statistically significant, but of little practical importance. For a given effect size and significance level, the larger the sample size, the greater the power of the associated test. |
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Term
| How does the population standard deviation affect power? |
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Definition
| Population Standard Deviation (σ): Variability in the process can obscure the signal, rendering the test less powerful. It is closely related to sample size - the more variable the data, the larger the sample size needed to detect an effect of a given magnitude. With the exception of the test for proportions, some measure of variability is required as an input to all power and sample size calculations. In general, the larger the population standard deviation, the lower the power. The problem is that we don't usually know the variance of the population! This problem can be resolved by using data from a pilot study to estimate the variance. It is also useful to keep in mind that paired and repeated measures designs have lower overall variability than those with independent samples. |
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Term
| Sketch the impact that varying a test's alpha risk has on its power. |
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Definition
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Term
Which of the following options is true? Power increases as:
A - Sample size decreases
B - Variance increases
C - Effect size decreases
D - Significance level increases |
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Definition
| D - Power increases as Effect size increases, variance decreases, sample size increases and significance (alpha) level increases. |
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Term
| A regional manager of a pharmacy wants to test whether there is a difference between the oder fill rates at the company's two locations. A previous study at location 1 found a fill rate of 90% (p1=0.9). What is the sample size required to detect an orde |
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Definition
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Term
| What is the basic philosphy behind Six Sigma? |
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Definition
| The idea that removing variability from upstream operations that are inputs to a process will yield defect-free outputs. Inputs are often referred to as "Xs" and outputs are referred to as "Ys". The output that we're concerned about is called Critical to Quality Characteristic (CTQC). |
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Term
| What are the central activities of a Six Sigma project? |
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Definition
| The only way to eliminate variation downstream is to find the sources upstream and reduce them. Identifying and resolving these upstream root causes of variation (or defects) are the central activities of a Lean Six Sigma project. |
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Term
| Sketch the process map for a Six Sigma process aimed at reducing call holding time. |
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Definition
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Term
| Where is much of the initial effort of a six sigmal process directed? |
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Definition
| Much of the initial effort of a Six Sigma project is to identify the X's (inputs), determine which inputs (X's) are significant, and quantify the relationship between those X's and Y (output). |
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Term
| Relate the Y = f(X) expression to our hold-time reduction project. |
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Definition
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Term
| Diagram a simplified relationship between the inputs of a process and the process outputs. Variability (defects) in the end product or service is a function of input variability, which is in turn a function of one or more root causes. |
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Definition
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Term
| What is the goal of Six Sigma? |
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Definition
| The goal of Six Sigma is to identify the significant inputs, then tackle the root causes of their adverse variability through improved process controls, error-proofing, redesign for manufacturabiltiy, and other methods. |
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Term
| Consider the new guest check-in process at a hotel. If Y=f(x), and Y is the time required to check in, what are some of the hotel factors you might consider Xs? |
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Definition
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Term
| What is Six Sigma according to Pande, Neuman, and Cavanagh in their book " The Six Sigma Way"? |
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Definition
| A comprehensive and flexible system for achieving, sustaining and maximizing business success. Six Sigma is uniquely driven by close understanding of customer needs, disciplined use of facts, data and statistical analysis, and diligent attention to managing, improving, and reinventing business processes. |
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Term
| List some of the benefits of Six Sigma process management. |
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Definition
Effective management of process improvement projects
Consistency of performance
Reduces fire fighting
Finds root-cause solutions to problems
gives an improved customer focus
leads to better informed management and better informed meetings |
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Term
| Which part of the DMAIC process would "define current and desired future process states" fall? |
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Definition
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Term
| Which part of the DMAIC process would "reduced cycle time" fall? |
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Definition
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Term
| Which part of the DMAIC process would "prevent defects" fall? |
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Definition
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Term
| Which part of the DMAIC process would "reduce defects and improve material flow" fall? |
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Definition
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Term
| Which part of the DMAIC process would "document processes" fall? |
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Definition
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Term
| Which part of the DMAIC process would "process reliability" fall? |
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Definition
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Term
| A mortgage company identified 35 possible defects that could occur during a loan application. Their records show that 2,500 loans were processed last year, and out of those loans, 3,500 defects were identified. So what is the sigma level? |
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Definition
Each of the 2,500 loan applications represented 35 defect opportunities, for a total of 87,500 opportunities. Actual experience was 3,500 defects.
Defects per million opportunities is therefore: (3,500/87,500) x 1,000,000 = 40,000
At a level of 40,000 Defects Per Million Opportunities, the company is operating at a Sigma Level between 3.0 and 3.5. |
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Term
| A bank determined that loan approval process has 25 defect opportunities. During the recent quarter, the bank processed 373,560 mortgage applications. On those, 57,400 errors were corrected. What is the DPMO and Sigma Level for the process? |
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Definition
DPMO = (# Defects x 1,000,000) / ((# Defect Opportunities/Unit) x # Units)
DPMO = (57,400 x 1,000,000) / (25 x 373,560) = 6,146
From the Six Sigma Conversion Table, you can see that a DPMO level of 6,146 corresponds to a Sigma Level of 4.0. |
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Term
| Co builds deck furniture. 7 different defects can arise in chair mfg. Over six months it built 1,746,932 chairs. During that period, 14,566 defects were noted. What is Company's defects per million opportunities (DPMO) level and sigma level? |
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Definition
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Term
| What are some of the more familiar tools that are employed within the Six Sigma structure? |
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Definition
Process Mapping
Statistical Process Control
Design of Experiments
Error-Proofing
Measurement System Analysis
Failure Mode and Effects Analysis |
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Term
| What is the acronym DFSS mean? |
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Definition
| Six Sigma also includes Design for Six Sigma (DFSS) methodologies and tools for developing new products, services and processes. DFSS provides a pathway to marketable innovation. Like DMAIC, practicing DFSS means focusing on customer requirements and instituting practices to assure requirements are met at near perfection. |
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Term
In which phase of the Six Sigma improvement process are performance standards defined?
Define
Measure
Analyze
Improve
Control |
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Definition
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Term
In which phase of the Six Sigma improvement process are potential solutions identified and evaluated?
Define
Measure
Analyze
Improve
Control |
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Definition
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Term
| More than anything the DMAIC process is what? |
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Definition
| More than anything, the DMAIC process is a systematic critical thinking exercise - a process of asking and answering questions. |
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Term
What is definition of defect?
A - variable product/process (PP)
B - PP doesn't perform as well as competition
C - PP doesn't meet customer requirements for use
D - PP that is unreliable
E - PP requiring extra processing |
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Definition
| C - A product/process that does not meet customer requirments for use. |
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Term
What is primary Six Sigma approach to reducing defect level?
A-Add inspection
B-reduce process variability
C-Revice specifications to better reflect customer expectations
D-Add workforce incentives
E-Manage Customer Expectations |
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Definition
| B-Reduce process variability at the source through redesign or process controls. |
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Term
What is the strongest guiding force of Six Sigma decision making?
A-Process owner experience
B-Historical best practices
C-Opinions of Senior Management
D-Data and statistical analysis
E-Benchmarking studies of competition |
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Definition
| D - Data and statistical analysis are the strongest guiding force for Six Sigma decision making. |
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Term
| Company provides two services. Process A can be defective 15 different ways. Process B only 5 ways. Company produces 500 As and 1000 Bs. A total of 27 defects experiences. What is DPMO for overall process? |
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Definition
DPMO (Defects Per Million Opportunities)
DPMO = (27 x 1000000)
divided by (15 x 500)+(5 x 1000)
DPMO = 2160 |
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Term
A company generates 22,700 defects per million opportunities. What is the Sigma level performance of the company?
A-4.0
B-3.7
C-1.2
D-2.8
E-3.5 |
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Definition
| 22,700 defects = 3.5 sigma level performance and a Cpk of 1.167 (sigma level/3). |
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Term
At what step in the Six Sigma improvement process are efforts made to identify the root cause of process variability?
A-Define
B-Measure
C-Analyze
D-Improve
E-Control |
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Definition
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Term
At what step in the Six Sigma improvement process is a Process map of the process created?
br>A-Define
B-Measure
C-Analyze
D-Improve
E-Control |
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Definition
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Term
Which of the following is NOT part of a value stream?
A-Process inputs from suppliers
B-The channel of distribution
C-Cost comparison by consumers
D-Processes that transform materials or information
E-New order processing |
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Definition
| C-Cost comparisons by consumers |
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Term
Which is NOT a reason to map the value stream?
A-To document who is responsible for specific actions.
B-Identify process inputs
C-Identify waste sources
D-Communicate the process graphicaly
E-Identify internal/external customers |
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Definition
A-To doumnent who is responsible for specific corrective actions.
The purpose of a value stream is to map the process to show the inputs, outputs, suppliers and customers involved in the process. Its objective is not to document who is responsible for specific corrective actions. |
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Term
Sorting through error data from a shipping process, a team wants to develop action priorities. What tool should the team analyze the data with?
A-Process Mapping
B-Brainstroming
C-Pareto Chart
D-Corrective Action Matrix
E-Trend Chart |
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Definition
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Term
| "Process Improvement" refers to a strategy of finding solutions to eliminate the root causes of performance problems in a process that already exists in your company. What is the Six Sigma approach? |
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Definition
Process improvement efforts seek to fix problems by eliminating the causes of variation in the process while leaving the basic process intact. In Six Sigma terms, Process Improvment teams find the critical Xs (causes) that create the unwanted Ys (defects) produced by the process.
Define the problem and what customers require
Measure the defects and process operation
Anaylze the data and discover causes of the problem
Improve the process to remove causes of defects
Control the process to make sure defects don't recur. |
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Term
| Break down the DMAIC components for a Process Improvement problem. |
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Definition
Define: identify the problem
define improvment requirements
set direction goals
Measure: validate problem/process
refine direction goals
measure key steps/inputs (Xs)
Analyze: develop causal hypothesis
identify 'vital few' root causes
validate hypothesis
Improve: develop ideas to remove root causes
test solutions
measure results
Control: establish standard measures to maintain performance
correct problems as needed |
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Term
| What does the acronym CTQ mean and why is it important to the Six Sigma process? |
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Definition
CTQ - Critical to Quality
The first step in calculating sigma or in understanding its significance is to grasp what your customers experct. In the language of Six Sigma, customer requirements and expectations are called CTQs. |
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Term
| Calculating sigma for Pizza business. Four quality requirements are: correct ingredients, hot, on time, and undamaged (4 defect opportunities for each pizza). 500 pizzas delivered had 25 late, 10 too cold, 7 damaged, 16 wrong ingredients. What's sigma? |
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Definition
To calculate sigma, take the total number of defects counted, divide by the total number of units tested multiplied by the number of defects possible per unit.
(25+10+7+16)/(500X4) = 0.029 defects per opportunity (DPO) or 29,000 defects per million opportunities (DPMO) which equals 3.4 sigma (97.8% yield). |
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Term
| What is the primary approach employed by Six Sigma to reduce the number of defects? |
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Definition
| Reduce process variability at the source through redesign or process control |
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Term
| What is the primary purpose of Six Sigma? |
|
Definition
| Improve profitability and/or other key performance metrics |
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Term
| What is the strongest guiding force of Six Sigma decision making? |
|
Definition
| Data and statistical analysis |
|
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Term
| At what step in the Six Sigma improvement process are efforts made to identify the root cause of process variability? |
|
Definition
|
|
Term
| At what step in the Six Sigma improvement process is a Process Map of the process created? |
|
Definition
|
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Term
| Processes that include steps where value is created as defined by the customer are called what? |
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Definition
| Value Stream or Supply Chain. Six Sigma strives to eliminate activities that don't produce value |
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Term
| What is the purpose of a value stream map of the process? |
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Definition
| To show inputs, outputs, suppliers and customers involved in the process. Its objective is not to document who is responsible for specific corrective actions. |
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Term
| A team is sorting through error data from a shipping process and wants to develop priorities for action. What tool should the team use to analyze the data? Process Mapping, Brainstorming, Pareto Chart Corrective Action Matrix, Trend Chart |
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Definition
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Term
| Team's working on a project to accelerate accounts receivable collections. They want to eliminate redundant or wasteful process steps so overall cyle time can be improved. What type of process map would be best choice? SIPOC Map, Flow Chart, Value Added |
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Definition
|
|
Term
Why are control limits set at +/-3 sigma?
A-3 std devs gives adequate room for process to vary over time
B-They represent the best balance between control and chaos
They provide the best economic balance between false signals and no signal. |
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Definition
| C-They provide the best economic balance between false signals and no signals. |
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Term
What is the basis of the theory of statistical process control?
Control Theory
Law of Averages
Laws of Probability
Correlation Analysis
Law of Unintended Consequences |
|
Definition
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Term
| A Six Sigma team at an insurance company has been working on a project to reduce the number of claim defects leading to denied claims. A control chart of claim denials is out-of-control. What conclusion should the team draw from this condition? |
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Definition
| The process is unstable over time. |
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Term
| A Six Sigma team is working to reduce the frequency of medical errors, and wishes to track the number of errors per patient per day. Which type of attribute control chart should the team use? c Chart, p Chart, np Chart u Chart or cp Chart? |
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Definition
| The u chart would be correct because it measures defects per unit (errors per patient) and accomodates a varying sample size. If a constant sample size were used, the X and Moving Range chart would be appropriate. |
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Term
| A diagnostic lab chartered a Six Sigma team to reduce the sample frequency with label problems. The team wishes to chart the % of samples with a label problem. Volume is high and stable enough to assume a constant sample size. Which attribute chart? |
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Definition
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Term
| Six Sigma team is works to reduce bad debts by tracking $ receivables over past 90 days. Using Individuals and Moving Range chart, avg balance outstanding is $736,50, and Median Moving Range is $58,000. What is upper control limit for Individuals chart? |
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Definition
$918,620
The Upper Control Limit of an XmR chart using the median moving range is: X-bar plus 3.15 times the median moving range, or $736,500 + 3.14x$58,000. |
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Term
| A Six Sigma team within the Finance Dept works on a project to reduce the # journal entry errors, which delay monthly closing process. Team wishes to track the % of erroneous entries using a p chart. If p-bar is 0.036 and n=2,000, what is the UCL? |
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Definition
0.048
The Upper Control Limit is: p-bar plus 3 times the square root of ((p-bar times (1 minus p-bar))divided by n) or 0.036 plus 3 times the square root of ((0.036 times (1 minus 0.036))divided by 2000). |
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Term
| An order processing operation has a specification of 4.0 hours +/- 1.0 hours. The process mean is 4.2 hours, with a std dev of 0,25 hrs. The process is stable and normally distributed. What is Cp and Cpk for the process? |
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Definition
Cp=(USL-LSL)/(6x sigma(short term))
Cp=(5-3)/(6x 0.25) = 1.33
Cpk=minimum (USL-Xbar or Xbar-LSL)/(3x sigma(short term))
Cpk = 1.07 |
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Term
| A Six Sigma team wishes to calculate Cpk in order to assess the capability of an order entry process. The team has determined that the process data are not normally distributed (distribution is skewed). What should the team do? |
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Definition
| Transform the data to more closely fit a normal distribution. |
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Term
| There are three primary categories of investigation in the Analyze phase of the DMAIC cycle. What are they? |
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Definition
Characterize the current process (What is the current state of affairs?) - Analyze I
Compare Treatments (Which treatment, or action, is more effective?) - Analyze II
Model the Process (Understand Relationships, How does X impact Y?) - Analyze III |
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Term
| In the Analyze phase of the DMAIC cycle, one seeks to uncover various root causes impacting the process. How does the root cause determination work? |
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Definition
| The path to determine a root cause is not a straight line. We start with general experience and through deduction try to draw specific conclusions, theories, or hypotheses. Those hypotheses are then tested for "truth", and the results in turn alter our general understanding (induction). The loop continues to cucle through this process of deduction and induction until the hypothesis is confirmed. |
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Term
| A Six Sigma team at Acme Building is working on a project to reduce the frequency of shipping errors. The team is unsure of the root causes for the problem. What type of chart should be contructed to uncover root causes? |
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Definition
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Term
| What questions are Fishbone Diagrams used to answer? |
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Definition
What are the potentional root causes of a proble?
What category of process inputs represents the greatest source of variability? |
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Term
Which is a primary use of Fishbone Cause and Effect Charts?
A-Provide a project road map
B-Quantify relationship between input and output
C-Show process performance over time
D-Categorize process inputs by department
E-Identify po |
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Definition
| E-Identify potential root causes of variability |
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Term
A Six Sigma team wants to learn more about the causes of defects in an insurance claim submission process. Which two tools would be most appropriate?
Trend Chart & Pareto Chart
5-Why Analysis & Histogram
Fishbone Diagram & 5-Why Analysis |
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Definition
| Fishbone Diagram & 5-Why Analysis |
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Term
| What does Genichi Taguchi's Loss Function stiplulate? |
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Definition
| Genichi Taguchi's Loss Function stipulates that the total loss to society from poor quality increases in a geometric fashion as variability increases. Accordingly, products produced near the upper and lower specification are less "good" than products produced at the process target value, and there is little difference between products that are marginally acceptable and those that are marginally defective. |
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Term
| What's the essence of the Taguchi Loss Funtion? |
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Definition
| Producing parts closer to nominal and well within the specification limits yields a more robust and durable assembly -- so all "good" parts are not created equal. |
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Term
| Use four target figures to demonstrate the difference between measurement precision and accuraccy. |
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Definition
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Term
| A measurement system can be characterized in five ways: three in terms of location and two in terms of variation. |
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Definition
Location (average measurement value)
Measurement Stability refers to the capacity of a measurement system to produce the same values over time when measuring the same sample.
Measurement Bias or Accuracy is a measure of the distance between the average value and true value.
Measurement Linearity is a measure of the consistency of Bias over the range of the measurement device.
Variation Repeatablity assesses whether the same appraiser can measure the same part/sample multiple times with the same measurement device and get the same value.
Measurement Reproducibility assesses whether different appraisers can measure the same part/sample with the same measurment device and get the same value. |
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Term
| A measurement system produces values whose average deviates from the true value. Its degree of deviation varies along the scale of the measurement, but is consistent over time at each point on the scale.How would you characterize the measurement problem? |
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Definition
| Measurement Bias and Linearity. |
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Term
According to Taguchi's Loss Function, the loss to society from poor quality increases as a function of what?
A-Process Variability
B-Process Centering
C-Specification Limits
D-Internal Scrap Rates |
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Definition
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Term
| Which phase of the DMAIC process are "Histograms" primarily used? What are they used for? |
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Definition
Histograms are primarily used in the Analyze phase of the DMAIC process and are a useful tool to describe a group of data. The primary goal of all Six Sigma projects is to reduce process variability and improve the consistency of output. Histograms provide a visual map of variability (dispersion or spread) so they help establish priorities for action.
Histograms show centering, spread (dispersion), and shape (relative frequency) of the data.
Histograms are very useful in the Measure, Analyze, and Improve phases of the DMAIC cycle. If you need to answer any of these questions, the histogram is an appropriate tool.
How variable is the output of the process?
Does process output fall within specifications?
Have improvement actions been successful in reducing variation? |
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Term
| Why are control limits set at +/-3 standard deviations? |
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Definition
| +/-3 standard deviation limits provide the best economic balance between false signals and no signals. |
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Term
| What is the basis of the theory of statistical process control? |
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Definition
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Term
| Name the various types of control chart, including what type of data they are used with. |
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Definition
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Term
| What question does the use of "rational subgrouping" answer? |
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Definition
Can variation in this process be captured between subgroups?
How should we draw the subgroup samples?
Is there too much variation within subgroups (i.e., are control limits artificially wide?)? |
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Term
| XmR Charts can be used to answer what kind of questions? |
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Definition
Is a process stable over time?
If a process is stable, how capable is it?
What is the effect of a process change on the average or range of the output characteristics?
How will I know if a process becomes unstable, or the capability changes over time? |
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Term
| Under what conditions are p-Charts used? |
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Definition
| When you are working with attribute (discrete) data and you want to chart fraction defective when the sample size is variable or constrant (though usually greater than 50 data). The chart assumes that the process has a binomial distribution. |
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Term
| Under what conditions are np-Charts used? |
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Definition
| When you are working with attribute (discrete) data and you want to chart the number of defective units when the sample size is constant (usually greater than 50). This chart assumes the process has a binomial distribution. |
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Term
| Under what conditions are c-Charts used? |
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Definition
| When you are working with attribute (discrete) data and you want to chart the number of defects when the sample size is constant (though usuallyg greater than 50). This chart assumes that the process has a Poisson distribution. |
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Term
| nder what conditions are u-Charts used? |
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Definition
| When you are working with attribute (discrete) data and you want to chart the number of defects per unit when the sample size is variable or constant. This chart assumes that the process has a Poisson distribution. |
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Term
| What does the Central Limit Theorem state? |
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Definition
The Central Limit Theorem states that the distribution of sample means will tend to fallow a normal distribution even if the population that the samples are drawn from is not normally distributed.
While control chart constants are calculated using the assumption of a normal distribution, control charts are not very sensitive to the shape of the underlying distribution because control limits set at three standard deviations are relatively wide, |
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Term
| Can a process have a Cp in excess of one but still fail to consistently meet customer expectations? |
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Definition
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Term
| How do the two capability indicies (Cp or Cpk and Pp or Ppk) differ in meaning? |
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Definition
Capability analysis is performed when it is necessary to understand the ability of a process to meet requirements. Since performance to requirements is a fundamental question, capability analysis is a frequent activity in the Measure phase of the DMAIC cycle. Capability Analysis is also performed in the Improve phase to verify the effectiveness of actions that have been taken. Capability Analysis can be used to answer the following questions:
What is the potential of the process to meet customer requirements? (Cp, Cpk)?
What is the actual performance of the process relative to customer requirements (Pp, Ppk)?
How capable would the process be if it were perfectly centered on target? |
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Term
What should be done 1st to improve process capability (Cpk)?
A-Take actions to reduce common cause process variation.
B-Take actions to address special cause process variation.
C-Take action to center the process on the specification limits |
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Definition
B-Take actions to address special cause process variation, then
C-Take actions to center the process on specification limits, then
A-Take actions to reduce common cause process variation |
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Term
A Six Sigma team is working on a project in the order entry area to improve order accuracy and reduce cycle time. The team wants to analyze the variability in cycle time. What tool should be used?
Trend Chart, Fishbone Diagram, Benchmarking, or His |
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Definition
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Term
| A Six Sigma team of an insurance company has been working on a project to reduce the number of claim defects leading to denied claims. A control chart of claim denials is out-of-control. What conclusion should the team draw from this condition? |
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Definition
| The process is unstable over time. |
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Term
| A Six Sigma team is working to reduce the frequency of medical errors, and wishes to track the number of errors per patient per day. The sample size of patients varies from day to day. Which type of attribute control chart should the team use? |
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Definition
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Term
| A diagnostic lab chartered a Six Sigma team to reduce the frequency of samples with label problems. The team charts the percentage of samples with label problems. Volume is high and stable enough to assume constant sample size. Which type of chart? |
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Definition
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Term
| A Six Sigma team works to reduce the amount of bad debts and tracks the $ amount of receivables over 90 days past due (XmR and ImR charts). The avg balance outstanding is $736,500. The Median Moving Range is $58,000. What's the UCL for the Indiv. Chart? |
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Definition
UCL(X) = Xbar + (3.14xMedian mR)
$918,620 |
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Term
| A Six Sigma team works to recduce the # of journal entry errors, which are delaying a monthly closing process. The team gathered data over time and wishes to track % erroneous entries using a p chart. If p-bar is 0.036 and n=2,000, what's the UCL? |
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Definition
UCL = pbar + 3Sqrt((pbar(1-pbar))/n)
0.048 |
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Term
| After implementing process improvement actions, an SPC chart of the process shows consistent variability about the mean on the X-bar chart, but the Rchart shows 8 points below the R-bar line. What' happening? |
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Definition
| The process variability is exhibiting less variability between observations (part to part). |
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Term
| An order processing operation has specifications 4.0 hrs +/- 1.0 hrs. The process mean is 4.2 hrs with a std dev of 0.25 hrs. The process is stable and normally distributed. What is the Cp and Cpk of the process? |
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Definition
Cp = (5-3)/(6x0.25) = 1.33
Cpk = (5-4.2)/(3*0.25) = 1.07 |
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Term
| A Six Sigma team wishes to calculate Cpk in order to assess the capability of an order entry process. The team has determined that the process data are not normally distributed (distribution skewed). What should the team do? |
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Definition
| Transform the data to more closely fit a normal distribution. |
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Term
| An SPC chart of a process has several recent points outside its LCL. The team has taken actions to move the process that way so the out-of-control condition is a favorable shift. What should the team do to calcualte Cpk and assess process capability? |
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Definition
| Collect 20 additional points to confirm the process shift, confirm stability, then calculate Cpk from the data collected after the shift. |
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Term
| What is the purpose of the Analyze phase of DMAIC? |
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Definition
| Ultimately, the analysis that you perform is intended to identify and understand causal relationships, i.e., how does variable X (input) affect variable Y (output), so you can find the root cause of variation and reduce it. |
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Term
| What are the three primary categories of investigation in the Analyze phase of the DMAIC cycle? |
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Definition
Analyze I: Characterize the process (What is the current state of affairs)?
Analyze II : Compare treatments (Which treatment, or action, is more effective?
Analyze III : Model the process (Understand relationships, how does X impact Y?) |
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Term
| Describe the path taken in root cause analysis. |
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Definition
| We start with general experience and through deduction try to draw specific conclusions, theories or hypotheses. Those hypotehses are then tested for "truth", and the results in turn alter our general understanding (induction). The loop continues to cycle through the process of deduction and induction until the hypothesis is confirmed. |
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Term
| What is the "Ishikawa Diagram" used for? |
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Definition
| The Cause & Effect, or Fishbone diagram was first used by Dr. Kaoru Ishikawa in 1943. This diagram is used to identify all of the contribution root causes likely to be causing a problem. It's usually used in the Analyze phase of the Six Sigma DMAIC process to understand the sources of process variablity. The Fishbone Chart is an initial step in the screening process. After identifying potential root causes, further testing will be necessary to confirm the true root cause(s). |
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Term
| After identifying the potential root cause(s), what is the team's most appropriate next step? |
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Definition
| Take action to confirm (test) that the potential root cause(s) is/are the true toot cause(s) before pursuing corrective action. |
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Term
| In Regression terminology what do the following terms mean: r, R, Rsquare? |
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Definition
r-Pearson's correlation coefficient is a bivariate (2-variables) measure of association and can take a value between -1 and +1.
R-multiple correlation coefficient R expresses the degree to which two or more predictors are related to the dependent variable and can only assume values between 0 and 1.
Rsquare-means the same thing whether you square r or R: it is the coefficient of determination and gives the amount of explained variation due to the reqgression equation. |
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Term
Which is a primary use of Fishbone Cause and Effect Charts?
A-Provide a project road map.
B-Quantify relationships between inputs and outputs.
C-Identify potential root causes of variability
D-Categorize process inputs by department |
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Definition
| C-Identify potential root causes of variability. |
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Term
| What is the purpose of a Scatter Plot Diagram and in what phase of the DMAIC cycle is it most frequently used? |
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Definition
| Visually display the relationship between two variables, Analyze |
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Term
Which assumptions are common to both Ordinary Least Squares and Logistics Regression?
Error variance is constant across predictor levels
Error terms are normally distributed
Error terms are independent of each other |
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Definition
| Error terms are independent of each other. |
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Term
Which statement is true, based on logistic regression model regarding the impact of age on job permotion: Logit(Promotion)=-4.2+0.4*AGE.
Chances of being promoted decrease with age.
Chances of being promoted increase with age. |
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Definition
The chances of being promoted increase with age.
Other false statements:
Promotions are caused by increasing age
Promotions are linearly related to age |
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Term
| The Power of a test answers the question: If the null hypothesis is false, what is the probability that the data from the experiment will reject the null hypothesis? What are the biggest factors affecting power. |
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Definition
| Power is the chance of finding a significant effect when one does exist. Naturally, a high-powered test is desirable. The biggest factors affecting power are: size of the effect(bigger> power, significance level (greater>power), sample size (greater>power) and the population standard deviation (lower>power) |
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