Six Sigma Final
A clinic providing MRI services has been averaging 18.2 visits per day over the last several years. During recent months, however, the number of patient visits appear to have fallen. The clinic's director randomly samples orders over the last 30 days and finds a sample mean of 16.8 visits per day with a standard deviation of 2.7 visits. In order to test whether the average number of visits has gone down, a "t-test for one mean" is run. What is the null hypothesis for this problem?
H0: µ=18.2
What is the alternative hypothesis for problem 5?
H1: µ<18.2
Refer again to the Filtration Rate experiment. Due to an equipment problem, the process must be operated a the lower temperature setting. What combination of the other factor levels yields the highest filtration rate?
Low stir rate, High concentration
Which is the best example of Six Sigma purpose?
Meeting customer requirements.
An in-control process has been performing satisfactorily for some time; however, an improvement is now required. Your response is to:
Minimize the common causes to improve the process.
Which of the following is not a purpose of Design of Experiments?
Minimizing the noise in a process
Which of the following is NOT a characteristic of good leadership?
Motivation by Fear
Overproduction, scrap, waiting, and excess motion are all forms of:
Muda
From your homework constructing a histogram, which distribution type best approximates the set of data?
Normal
During the team development process, at what step do team members reconcile their competing loyalties, agendas, and responsibilities?
Norming
Which of the following statements reflects accurately the Kano Model?
Over time, Excitement Quality characteristics tend to become Basic Quality requirements.
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?
Pareto Chart
The following month, Step 2 of the same process from number 12 produced 9,523 units during the month with 381 defects occuring on 325 units. There are 3 defect opportunities per unit at this step of the process? During this month, Step 1 throughput yield was calculated to be 93.4%. What is the "Rolled Throughput Yield" for the entire 2-step process?
89.7%
This question refers to the process FMEA from the FMEA homework problem on seatbelt installation. Process improvement actions have reduced the frequency of misaligned trim cover clips by 2/3 which led to a corresponding drop in the Occurrence Rating by 2/3. What is the new RPN for misaligned trim cover clips?
8
Over the course of a week, a manufacturing plant experienced the following: 72 out of 1000 units had defects; 2.5 out of 80 scheduled production hours were lost due to minor line stoppages; and, 1.5 out of 80 scheduled production hours were lost due to equipment breakdowns. What was the Overall Equipment Effectiveness (OEE) for the month?
88%
A Six Sigma team is comparing a new treatment to the existing process and would like to be 95% confident in the conclusion. What is the risk, or significance level threshold for the decision-making process?
0.05
Review the ANOVA for the same Filtration Rate experiment. How much of the experimental variation is explained by the model (i.e. adjusted r-squared)?
0.949
An order processing operation has a specification of 4.0 hours + or - 1.0 hour. The process mean is 4.2 hours, with a standard deviation of 0.25 hours. The process is stable and normally distributed. What is the Cp and Cpk of the process respectively?
1.33, 1.07
Consider a company that produces two products using the same basic process. Product A is relatively complex, and can be defective in 15 different way. Product B is relatively simple, with only 5 possible defects. The company produces 500 units of A and 1,000 units of B. A total of 27 defects are experienced. What is the DPMO (Defects Per Million Opportunities) for the overall process?
2,160
Several potential revisions have been identified to improve the trend chart below.(1)Change the title (2)Use longer time horizon (3)Use narrower y-scale(4)Use wider y-scale (5)Use shorter time horizon (6)Indicate chart source(7)Set scale max. at 100% (8)Plot a trend line.
2,3,6,7
A Six Sigma team is trying out a new forming tool to reduce variability in a process that manufactures stainless steel fittings for a medical device. One of the significant dimensions has a process standard deviation of 0.35 mm. The team needs to know how many samples to collect in order to achieve an estimate of the mean with precision of + or - 0.15 mm, with 95% confidence. What sample size is required to meet this goal?
21
To answer this question refer to homework problem on Gage R&R. What is the R&R error as a percent of the total variation, and as a percent of the tolerance?
26.3, 26.9
An experiment is conducted to compare five treatments. The F-ratio for the experiment is 3.09. There are 4 degrees of freedom in the numerator, and 15 degrees of freedom in the denominator. Using the tables in the back of the DOE text, what is the critical F distribution value, and what statement can be made about the experiment with 95% confidence?
3.056, the difference in treatment did not occur by chance
A company generates 22,700 DPMO. What is the Sigma level performance?
3.5
A Six-Sigma project has a baseline performance of 16,800 DPMO. What is the sigma level?
3.625
A measurement system analysis was conducted that revealed total measurement error equal to 45% of the process tolerance. What is the general rule-of-thumb for minimum acceptability of a measurement system?
30% or less
A Six Sigma team is working to improve the capability of a two-step process. The team wishes to establish a performance baseline. In step 1 of the process, 9,705 units were processed during the last month. There are five opportunities for a defect on each unit. During the month 560 defects were found on 437 units. What was the "Throughput Yield" during that month for step 1 of the process?
94.2%
What is the definition of a defect?
A product/process that does not meet customer requirements for use.
A process has been experiencing problems lately. The operators charting the process have identified the cause to be due to a change in incoming materials. This problem is:
A special cause
What is a "sample" when used in hypothesis testing?
A subset of the population, used for the process of testing
The following question refers to an injection molding process to make refrigerator door handles. The door handle mold has four cavities (forms four handles at a time). A Six Sigma team is investigating premature door handle failures in the field, and suspects variation in thickness a a potential root cause. A snapshot of data from successive cycles is presented below, representing each of the four cavities over time, measured in millimeters (assume this data is representative of a larger sample). Cycle Cavity 1 Cavity 2 Cavity 3 Cavity 4 1 3.6 3.4 3.7 3.5 2 3.9 4.0 3.7 3.6 3 4.1 4.4 4.5 4.3 4 3.8 3.9 3.6 3.5
A. Subgroup by cycle - include output from each cavity.
A researcher believes that Drug A is more effective (has a larger mean) than drug B. What is an appropriate alternative hypothesis for any test he may conduct (note µ = mean)?
All of the above
A researcher believes that Drug A is more effective (has a larger mean) than drug B. What is an appropriate alternative hypothesis for any test he may conduct (note µ = mean)?
All the choices
Which of the following is not a primary role or responsibility of a Green Belt?
Allocate funds and human resources to Six Sigma project.
At what step in the Six Sigma improvement process are efforts made to identify the root cause of process variability?
Analyze
How would you categorize the cost of internal product/process testing?
Appraisal cost
Thought Process Maps are used to organize and document team activities. After answering the first question based on the first action taken, what is the most likely next step?
Ask another question.
After identifying several sub-categories (drivers) of customer needs/wants, the team is getting stuck trying to move to more specific requirements. What questions should the team ask about each of the drivers in order to identify CTQ characteristics?
Ask, "What does that mean?" until it would be absurd to continue.
The following refers to the Battery Life practice problem 7-1 from the DOE text. Assume that material A3 is substantially cheaper than the other materials. If material A3 is used because of its low price, which processing temperature should be selected to maximize battery life?
B1 and B2 are not significantly different
A measurement system is evaluated and found to produce values whose average deviates from the true value. The degree of variation varies along the scale of measurement, but is consistent over time at each point on the scale. How would you best characterize the problems with this measurement system?
Bias and linearity
An SPC chart of a process under study has several recent plot points outside of the lower control limit. The team has taken actions to move the process in this direction, so the out-of-control condition is a favorable shift. The team wants to calculate the Cpk in order to assess process capability. What should they do?
Collect 20 additional data points to confirm the process shift, confirm stability, then calculate Cpk from data collected after the shift.
This question refers to the reaction plan from the SPC lesson homework exercise. What does the chart champion/data collector do after a corrective action has been implemented to remove a special cause?
Collect seven additional subgroup samples to confirm effectiveness of the corrective action.
A Six-Sigma team working to improve injection molding performance has identified four significant inputs to a process, and has established a measurement basis for each input: temperature of V, average quality grade of W, color value of X using a color spectrometer, and speed (RPM) of Y. Identify whether each of these measurements is discrete or continuous, in order:
Continuous, discrete, continuous, continuous
What is the purpose of blocking?
Control the experimental impact of known uncontrolled variation.
Which of the following is not a function of the control plan?
Control the process of identifying significant characteristics.
Which of the following is not part of a value stream?
Cost comparisons by consumers
A CTQC can be defined as:
Critical to Quality Characteristics
Acme Office Equipment, an office equipment leasing company, has found that providing aggressive lease terms for new equipment is an important service to customers, driving substantial sales growth in recent years. However, delinquent payments, bad debt charge-offs, and equipment repossessions have reached a serious level at Acme. The Finance Department at Acme has chartered a Six Sigma team to address the Company's credit scoring model to make sure that the customers' payment history and financial conditions are evaluated properly, along with the equipment value, and expected depreciation over the term of the financing. Which of the following are only inputs to the Acme credit approval process?
Customer financial information, Expected Depreciation of Equipment
The guiding force of Six Sigma decision-making is what?
Data and statistical analyses.
At what step in the Six Sigma improvement process is a Process Map created?
Define
A control chart is used to:
Detect non-random variation in processes.
This question refers to the Injection Molding pratice problem 5-1 from the DOE text. Which three-way interaction is aliased with main effect D?
EFG
Which of the following is NOT part of the change leadership process?
Eliminate functional reporting structures.
Three of the following are categories of Error-Proofing techniques. Which one is not?
Elimination
Which test should be used to compare the variances of 2 independent populations?
F-test
Refer again to the Filtration Rate experiment. Which combination of factor levels yields the highest filtration rate?
High temp., High stir rate, Low concentration
Which of the following is a primary use of a Fishbone Cause and Effect diagram?
Identify potential root causes of variability
Which of the following is not a benefit of the Corrective Action Matrix?
Identify relationships between corrective actions.
Which of the following process sequences represents the proper order of steps in the measurement process?
Identify what to measure, determine how to measure, develop sampling and reaction plan, add to control plan.
What is the primary purpose of Six Sigma?
Improve profitability and/or other key performance metrics.
Critical Path is determined by which of the following?
In-sequence tasks with the longest combined lead time.
Who determines what is or is not a Best Practice?
Individual organizations based on their knowledge and experience.
A Six Sigma team is investigating customer complaints of visual defects in a product. To collect data for analysis, a sample of product is pulled at a point in the process immediately downstream from the process step in question (at a point visible to the process operators). The results of the sample analysis are quite different from the field experience reported by customers. If the discrepancy is due to error from the sample data collection scheme, what is the most likely cause given the location of the sampling relative to the operators?
Interaction bias
Which of the following is NOT a reason to use continuous (variable) data?
It is more convenient for subjective appearance items.
Which of the following Japanese techniques is most clearly identified with small incremental change?
Kaizen
The Visual Factory would be supported to the greatest extent by:
Kanban 5S B & C
A Six-Sigma team leader initiated a project to re-engineer the supply chain for a manufacturer of industrial fittings. The team leader communicated the project objective in clear terms. Since she was an avid NASCAR fan, conversation in team meetings seemed always to drift toward current events on the racing circuit. Many brainstorming sessions were conducted to examine how the supply chain could be improved if the whole company was reorganized. Team business was handled in a relaxed fashion that kept everybody happy. After six months, the project champion was growing increasingly frustrated by the lack of progress. From this brief description, which primary leadership characteristics were missing in the team leader?
Passion, Action-orientation
Which test should be used to compare 2 means when the population variances are unknown but assumed equal?
Pooled t-test
Refer again to the Injection Molding example. Which combination of booster pressure, cycle time, and moisture yields the lowest shrinkage?
Pressure Low, Cycle Time Low, Moisture Low
According to Taguchi's Loss Function, the loss to society from poor quality increases as a function of what?
Process variability
About 9 months after embarking on a Six-Sigma effort, a company moved from measurement with traditional micrometers and verniers to digital micrometers and two piece linear scales. Why was this action necessary?
Processes have improved and they needed finer product measurements.
What is the purpose of establishing the baseline performance level?
Provide a starting reference point to gage improvements.
Which is the best description of the term "Operational Definition?"
Provides a clear, unambiguous acceptance standard.
What do the "R" and "B" loops do in a Systems Diagram?
R reinforces the initial action immediately and B counteracts the effects of R after a delay.
Which three actions are correct to improve Visual Control?
Reduce inventory, clean and organize workstations, display performance charts.
What is the primary approach employed by Six Sigma to reduce the defects?
Reduce process variability at the source through redesign or process controls.
Three of these measurements gage Results, which one is best described as an Indicator/Predictor?
Scrap rate of a key input process
As part of a multi-factor experiment to improve paint quality (gloss level), the air pressure setting on a set of automated spray guns is being evaluated. What are the factor, level, and response variables for the experiment? in order:
Spray gun air pressure, pressure setting, gloss level
Which is the primary tool used to identify indirect effects and unintended consequences?
System Diagrams
Which of the following statements is most correct regarding Team Charters?
The Charter defines the project mission.
Which of these measurements are taken from a continuous scale?
The air pressure of the left front tire of your vehicle.
A manufacturer of bungee cords performed an FMEA on the final assembly process. One element of the process had an RPN much higher than the others. Which statement is true?
The element with a high RPN has higher risk, and should be a top priority for corrective action.
What is the basis of the theory of statistical process control?
The laws of probability
Which of the following is a Supporting Service Requirement (vs. Primary Output Requirement)?
The order-entry function is efficient and customer-friendly.
After implementing process improvement actions, an SPC chart of the process shows consistent variability about the mean on the X-bar chart, but the R chart shows eight points below the R-bar line. What is happening?
The process is exhibiting less variability between observations (part to part).
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?
The process is unstable over time.
The expression Y = f(x) is often used to describe the relationship between process inputs and the process output. Which description of Y = f(x) is most appropriate?
The process output (Y) is a function of the process inputs (x).
Which of the following is not a reason to map the value stream?
To document who is responsible for specific corrective actions.
Which of the following is not a direct benefit of Brainstorming?
Track who is supposed to do what, when.
A Six Sigma team wishes to calculate Cpk in order to assess the capability of a process of filling gel-caps (gelatin capsules) with medication. The team has determined that the process data are not normally distributed (the distribution is skewed). What should the team do?
Transform the data to more closely fit a normal distribution.
What is the false rejection of the null hypothesis called?
Type I error.
The term Experimental Noise refers to which of the following?
Uncontrollable variation due to different people or machines
What action could you take to help your team progress through the storming phase?
Use the S.M.A.R.T. process to guide objective/goal setting.
Which of the following is a component of Design for Manufacturing?
Use the minimum number of parts possible.
Two variables (A & B) have a correlation coefficient (r) of 0.74. Which of the following is a true statement?
Variation of one variable explains 55% of the variation in the other
What is the purpose of the CHECK process?
Verify that the established process is being followed. Verify that the operators have the correct tools to do the job. B & C
Which method should be used to make an inference of the mean of a population when the population variance is known?
Z-test
A diagnostic lab has chartered a Six Sigma team to reduce the frequency of samples with label problems. The team wishes to chart the percentage of samples with a label problem. Volume is high and stable enough to assume a constant sample size. Which type of attribute control chart should the team use?
p-Chart
The probability of getting a test statistic at least as extreme as the observed test statistic (computed from the sample) under the assumption that the null hypothesis is true, is called the:
p-value
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?
u-Chart
