SSGI SixSigma Green Belt: Chapters 10 thru 19
A sample of 25 customer orders is selected. It is found that two orders had errors. In the first of these, two errors were found. In the second, three errors were found. No other errors were encountered. The DPU is _____ .
0.20
A company places a order from its supplier for 100 units. When the order arrives a sample of 10 units is selected and tested. Each test measures four dimensions of the units. They include color consistency, quality, included instructions and packaging. Of the ten units sampled there are a total of three problems found in two of the units. One unit had a single problem and other had two problems. The DPU is ___________ .
0.3
A process starts with 100 good pieces and 85 are produced. The FTY is ___ .
0.85
The Z table tells us that the area under the normal curve to the left of Z value of 1.5 is 0.9332. The area under the normal curve between plus and minus Z=1.5 is _______ .
0.8664
A process has three steps. The yield on each step is 0.9. What is the yield (RTY) of the process?
0.9 x 0.9 x 0.9
A Six Sigma process is one that produces products or delivers services such that there are fewer than ___ defects per million opportunities.
3.4
The average wait time at call center is 7 minutes with a standard deviation of 1 minute. A customer has called and has waited 10.5 minutes. What is the Z value?
3.5
The mean of a process is 45. if the standard deviation of the process is 2, a process that has been set to Six (6) Sigma would produce 99.9997 percent of its parts between _____ and ____ .
33 to 57
If the Z value is zero, then _____ percent of the area under the curve is less than the mean.
50
Suppose samples are taken at periodic intervals from an operational process. What is the likelihood that a range of plus or minus one standard deviations (in this case it is more correct to say one standard error of the mean) will capture a single sample from the process?
68
If 100 items are sampled and one unit is found to have three defects, another is found to have one defect, and a third is found to have four defects. The remaining units have no defects. How many "Defects" have been found?
8
The Pareto Principle states that _______ percent of the problem can be traced to _______ percent of the possible causes.
80,20
There are 40 possible defects that can occur when manufacturing a single part. Suppose a sample of 30 parts is taken. The total number of defects found in the sample is 10. What is the DPMO?
8333
In a chip manufacturing process, 5,000 chips began the process. At the end, only 4,500 pass quality control tests. The FTY would be ___ percent.
90
A Z value of ±2 will include _____ percent of the observations under the normal distribution.
95
If 100 pieces are started but 95 acceptable pieces finish, the First Time Yield would be ______ percent.
95
The probabilities associated with tossing a coin wold be represented by a ________________ distribution.
Binomial
The probability of getting exatly two heads in two tosses of a coin would be called a _________________ probability.
Binomial
Chi Square tests are used when count data is presented in a _______________ table.
Contingency
The number of defects per unit sampled is measured by ______ .
DPU
Problem finding is primarily associated with which phase of the DMAIC process?
Define
The ratio of good parts produced at the end of a process divided by the number of parts that were started is called ______ .
FTY
A Fishbone diagram cannot be used when several causes contribute to a problem.
False
A Histogram and Line Chart are basically the same.
False
A Six Sigma designed process is one that produces products or delivers services such that there are fewer than 340 defects per million opportunities.
False
A Six Sigma designed process should have no defects per Unit.
False
A control chart is a line chart with additional information that includes a target level together with an upper target limit and lower target limit.
False
A manufacturer of headphones finds that an increasing number of phones have failed to pass the final quality control check before they are shipped to a distributor. This suggests Special Cause variation.
False
A process has a mean of 150 and a standard deviation of 10. Six sigma limits will be 110 and 210.
False
A restaurant quality control system has been designed as a Five Sigma process. Its goal is to ensure that food is free of contaminants. If 10,000 meals are served each month about 100 meals would have traces of contaminants.
False
A sample can be larger than the population from which the sample is taken.
False
A sample is taken from the output of a process. The likelihood that this sample will fall within two standard errors of the mean from the process mean is 68%.
False
A scatter plot is a common Six Sigma tool for finding the root cause of a problem.
False
A scatter plot is a tool used exclusively in a lean analysis.
False
A successful Six Sigma project outcome should not depend upon finding the root cause of the problem.
False
According to the central limit theorem, the distribution of sample means can not be represented as a normal distribution.
False
An ordered histogram is a histogram that sorts outcomes by date from earliest date to latest date.
False
As the standard deviation gets larger, the variation in the data gets smaller.
False
By drilling down through histograms the one root-cause that explains the overall problem can always be found.
False
Consider a help line for those who have just purchased a virus protection program for their computer. The variation in the length of time it takes for a caller to reach a representative - under the assumption that the process is behaving as expected - would be considered a Special Cause variation.
False
Every process should set Six Sigma as a quality goal.
False
For large size samples, in the range of 200 or more, the distribution of sample means will not be closely clustered around the mean of the population.
False
If the RTY is 80 percent, the likelihood that a process will suffer a failure or reject is 80 percent.
False
If the range of a data set is relatively narrow, the standard deviation will be relatively large.
False
In a Multi-Vari chart, the range of variation is expressed along the "X" or horizontal axis.
False
In a normal distribution most of the data items cluster toward the ends or tails of the distribution.
False
In problem finding, it is often enough to identify the symptom of the problem, since it is the symptom that must be corrected first.
False
It is customary to set the UCL and LCL at plus and minus one standard error of the mean from the mean of the process.
False
It is not unreasonable to set surgical procedures at a hospital to a standard of Three Sigma.
False
Multi-Vari Charts display the root cause of a problem
False
Multi-Vari charts also uncover why special cause variation occurs.
False
Ninety-five percent of the observations in a normal distribution fall above the mean.
False
No more than three categories can be used in Pareto Chart.
False
Only one defect can occur in one unit.
False
Only the process mean needs to be monitored to assure that a process is in control.
False
Several employees at a distribution center have reported ill and have been replaced by temporary help. The number of errors have increased. This would be considered common cause variation.
False
Six Sigma focuses on process efficiency.
False
Six Sigma limits imply that outcomes beyond six standard deviations on either side of the mean will never occur.
False
Sometimes an LCL is not necessary to determine whether or not the process is in-control or out-of-control.
False
Special cause variation is always present. No process can avoid it
False
The "Y" or vertical axis on the histogram displays user-specified ranges.
False
The Oblique lines in a Fishbone diagram designed to uncover the root-cause of a problem in operations would include Promotion and Prices.
False
The acronym DPMO means Defects Per Multiple Operations
False
The bars on a histogram represent categories of complaints received by a customer service department. In an ordered histogram the shortest bar represents the category that needs to be addressed first.
False
The binomial distribution represents discrete processes, those that have more than two possible outcomes.
False
The closer are the observations in a distribution, the larger is the standard deviation.
False
The distribution of sample means will only be symmetrical if the population is symmetrical.
False
The focus of Six-Sigma is on Common Cause variation.
False
The greater is the variation of data around the mean, the smaller will be the standard deviation.
False
The greater is the variation of data in a dataset, the lower will be the standard deviation.
False
The greater the variation in a data set, the smaller will be the Standard Deviation.
False
The head of the Fishbone represents the root-cause of the problem.
False
The horizontal lines that intersect the oblique lines in the Fishbone diagram represent the major categories into which causes can be placed.
False
The length of time it would take to be seen at a health care clinic, that has otherwise not expected emergencies during the day, would be subject to special cause variation.
False
The longer is the vertical line in a Multi-Vari chart the lower is the "position" variation.
False
The mean output of a process is the major factor in controlling that process and ensuring that it meets process objectives.
False
The percent of the data or observations between minus one standard deviation from the mean and minus three standard deviations from the mean is 60 percent.
False
The process mean for a service process is designed to serve an average of 10 customers per hour. During the day, a sample of customers is taken and it is found that only 9 customers have been served during this period. This is an unlikely outcome since the sample mean and process mean should be the same.
False
The purpose or function of a Pareto Chart is the same as a Scatter Diagram.
False
The range is a measure of variation that uses every item in a data set.
False
The special properties of the normal distribution apply to a distribution whether or not it is normally distributed.
False
The standard deviation for waiting time at a clinic should be large to accommodate those who arrive late for appointments.
False
The standard deviation is a measure or "statistic" that is used to quantify the variation in a data set and is represented by the letter "X".
False
The standard deviation of the population is 50, the sample size is 25. The standard error of the mean is 2.
False
The variation of the distribution of sample means is the same as the standard deviation of the population.
False
There is no difference between DPU and DPMO.
False
There is no difference between the concept of a sample mean and a process mean.
False
There is only one source of variation.
False
Two statistics can be used to summarize a distribution. They include the mean and average.
False
When a process produces output that exactly corresponds to the expected or desired mean of the process, then it is not possible for the variation in output to exceed expectations.
False
When designing a process that serves customers, effort should be made to design the process such that the standard deviation is large.
False
When process output falls above or below the target level the process would be considered out-of-control.
False
When several samples are taken from the same population and at the same point in time, each sample mean should be exactly the same as the others.
False
When the population is not normally distributed, sampling theory cannot be used to monitor and control an operational process.
False
The number of good units or pieces produced divided by the number of total units that originally started through the process is measured by the _______ .
First Time Yield
When the Z Value is +3 which of the following best represents the area under the normal curve to the right of the Z value?
Less than 1%
If you need to determine the probability that exactly five calls will arrive at the call center between 8 and 9 AM today, what probability distribution could be used to provide the answer.
Poisson
Which of the following represents the likelihood that a process will complete all of the required steps without any failures or rejects.
RTY
A Chi Square distribution is used to evaluate the difference between counts
True
A Fishbone diagram to uncover the root-cause of problems in customer satisfaction would include such categories as product quality, price and call center support.
True
A Pareto Chart includes two vertical-axis.
True
A Pareto Chart is a combination of a histogram and line chart.
True
A SIPOC chart can be useful in identifying input variables for use in the Multi-Vari chart
True
A company is interested in the response to a promotional item given to fans who attended a Miami Dolphins game. They have sampled 100 fans and asked them to write a review. Those who attended the game would be considered the population.
True
A control chart could be used by an internet hosting company to monitor the percent of customers who would recommend the service to their friends.
True
A cumulative percent for each user-defined category must be calculated to create a Pareto Chart.
True
A histogram can be used to display the length of time it takes a warranty center to repair a unit.
True
A histogram is a graphical representation that organizes a group of data into user-specified ranges.
True
A line chart without a target, UCL and LCL is not very useful for monitoring and controlling process output.
True
A more common standard for the design of a monitoring process is to choose a Four Sigma standard
True
A multi-vari analysis is visual and uses no statistics to compare output variation.
True
A repair facility for camcorders that are still under warranty takes an average of four weeks to process a repair request. The company should consider lean methodologies to improve mean process time.
True
A root cause is a situation or problem that prevents a final and desirable event from occurring.
True
A root cause is different than a symptom.
True
A scatter plot can be used to display the results of samples taken at intervals over time.
True
A single sample mean is not likely to fall near the tails of the population distribution since a sample is unlikely to include only results from one end of the population. In most situations a sample may include a few values relatively far from the population mean with most of the values selected nearer the center of the population.
True
A t distribution is used to determine probabilities when the sample is small.
True
A t-Test is used to determine the difference between two samples when the sample sizes are small.
True
An ordered histogram displays the occurrence for each category from highest to lowest with the highest typically on the left.
True
An organization wishes to determine if the variation across five processes is different. A multi-vari analysis could be used.
True
As long as a process is in-control and performing as expected there is not much that can be done to eliminate common cause variation short of redesigning the entire process.
True
As the sample size increases, any single sample result is very likely to be closer to the population mean.
True
As the sample size increases, the standard error of the mean will decrease.
True
Barring any accidents, the length of time it takes to commute to work is subject to common cause variation.
True
Based on the examples in this chapter, the oblique lines in a marketing Fishbone diagram would include Product, Place, Price and Promotion.
True
Common Cause variation is predictable.
True
Defects Per Unit (DPU) is the number of defects in a sample divided by the number of units sampled.
True
Designing a process that produces output with little or no variation from one unit to the next can be very costly.
True
Fishbone diagrams are similar to Pareto charts in that they are used to drill down and find the root-cause of a problem.
True
Fishbone diagrams break a problem down into successive layers each one representing the possible root-cause of a problem.
True
For large size samples, the distribution of sample means is symmetrical and centered on the population mean.
True
Four identical machines in a manufacturing process are operated over three shifts. A multi vari chart would be appropriate to study the variability of each machine and then to determine which machine contributes most of the output variation
True
If common cause variation is inherent in processes, this means that achieving a standard deviation of zero for a process is all but impossible.
True
If the highest number in a range is 40 and lowest is 22, an estimate of the standard deviation is 3.
True
If the standard deviation of one data set is greater than the standard deviation of another, the values in the data set of the first data set are more widely dispersed than the values in the second.
True
In Multi-Vari analysis, a graph is created that displays the possible sources of variation affecting process output.
True
In a Six Sigma designed process half of the outcomes will occur above the mean of the process.
True
It is not possible to eliminate all common cause variation in most processes.
True
Line charts can display sample results. Time is measured on the X or horizontal axis.
True
Managers often treat symptoms not root causes.
True
Many distributions describing natural processes such as IQ (Intelligence Quotient) or height can be classified as normal distributions.
True
Multi-Vari charts also display output means
True
Multi-Vari charts can combine variables. One example is displaying the relationship between call duration, location and time of day on the same chart.
True
Normal distributions have special properties that specify the percent of observations or data that fall within a specified number of standard deviations from the mean.
True
One hundred samples are taken from the same population. The sample means are grouped and these groups are displayed as a histogram. A distribution of sample means can be obtained by drawing a smooth curve through the top of the bars in the histogram.
True
One of the principles of Six Sigma is to monitor and control variation of output.
True
Problem finding is often the first step in a Six Sigma analysis.
True
Problem finding when searching for the source of a Six Sigma related projects is not very different from the challenge of problem finding when a physician examines patients to find the source of their symptoms.
True
Process output is summarized by a statistic called the process mean. However, every unit of output from the process commonly varies from one unit to the next.
True
RTY represents the likelihood that a process will complete all of the required steps without a failure.
True
Regardless of the shape of the population distribution, the distribution of sample means will be normal when the sample size is large.
True
Several people working at a call center have called to report that they are sick with the flu and have been replaced by temporary help. Call waiting time has increased significantly. This would be considered special cause variation since it is not inherent in the process and is not predictable.
True
Six Sigma is a measurement-based, process improvement and variation reduction approach that focuses on dependable process output that meets product or service goals.
True
Sixty- Eight (assume rounding) percent of the observations or data in a normal distribution fall between the mean and plus or minus one standard deviation from the mean.
True
Sometimes it will be necessary to drill down to lower-level histograms to find the root source of a problem.
True
Special cause variation is of most concern in Six-Sigma. It is unexpected and can disrupt process output.
True
Special cause variation represents the category of variation that effective Six Sigma monitoring systems are expected to detect.
True
The Pareto Chart in Lean Six Sigma Analysis can be used to display the cumulative percent of the overall problem that will be addressed when one or more individual problem areas are eliminated.
True
The Poisson distribution focuses on the number of discrete occurrences over a defined interval.
True
The Standard Deviation can be computed in an Excel spreadsheet.
True
The benefit associated with using the standard deviation over the range as a measure of variation is that the standard deviation is a statistical measure that takes into consideration every item in the data set.
True
The benefit of the standard deviation over the range is that it uses every data item in the dataset to measure variation not just the lowest and highest values.
True
The concept of Six Sigma implies near perfection.
True
The data or observations that fall under the normal distribution between plus one and plus two standard deviations from the mean is 13.6 percent.
True
The data within a vertical bar of a Multi-Vari chart is referred to as "within variation" or "position variation."
True
The goal in an emergency department is to register and process all patients quickly. This suggests that if patient registration and processing times were recorded, the standard deviation of this data set should be small.
True
The head of the fish in a Fishbone diagram represents the problem whose root-cause needs to be uncovered.
True
The length of the vertical lines in a Multi-Vari chart represents the range of a specific variable over a specific period such as one week.
True
The length of time it takes to reach a sales representative on the phone can be represented by both the mean and a measure of variation.
True
The major problem with setting a Six Sigma standard for a process is the cost of achieving this level of quality.
True
The mean represents the "centralness" of a data set while the standard deviation represents the extent to which data items vary around the mean.
True
The mean represents the centralness of a distribution
True
The mean represents the centralness of a distribution.
True
The normal or expected cause of variation is called Common Cause.
True
The number of data points or observations beyond plus and minus six standard deviations from the mean would be much less than one percent.
True
The oblique lines in a Fishbone diagram represent the major categories within which the root-cause of the problem may be found
True
The ordered histogram usually shows that a significant share of the problem can be attributed to one or a few sources or categories.
True
The problem with designing a Six Sigma process is that it can be quite costly to operate with such high quality standards.
True
The process mean represents the average result associated with producing units of output from an operational process.
True
The range can be used as a measure of variation.
True
The range of one data set is from 20 to 80. A quick estimate of the standard deviation is 10.
True
The special properties of the normal distribution used to make statements about population distributions can also be used to make statements about the distribution of sampling means. So, 68 percent of the samples means will fall within plus or minus one standard error of the mean from the mean of the distribution of sample means.
True
The standard deviation measures the variation of the population distribution but the standard error of the mean measures the variation of the distribution of sample means.
True
The standard deviation represents the extend of the spread of the data in a dataset
True
The standard deviation represents the extent of variation in a distribution.
True
The vertical bar on the right-hand side of the Pareto Chart identifies the category that contributes least to the problem.
True
To find the root-cause of a problem it may be necessary to drill down through more than one histogram.
True
To improve scheduling patients through an MRI, the standard deviation for the length of time it takes to complete the process for specific scans should be a small as possible.
True
Using the special properties of the normal distribution, 99.7 percent of the data in a normal distribution will fall between the mean and plus or minus three standard deviations from the mean.
True
Variation in the time it takes to process patients through a clinic can lead to bottlenecks as some patients take much longer than expected.
True
When the DPMO is 6,210 this suggests a process that has been set to a standard of Four Sigma.
True
When the consequences for failing to meet high standards are significant, such as in many areas of health care, Six Sigma standards of product or process design are justifiable.
True
When the standard deviation is large, the spread of the data around a mean is larger than if the standard deviation were small.
True
When the standard deviation is larger in dataset A than it is in dataset B, this suggests a wider dispersion of the data from the mean in dataset A.
True
The two parameters used to manage processes include the ___________ and __________ .
mean and variation
Two statistics that define a normal distribution are the ________ and the ___________ .
mean, standard deviation
A histogram can be used to display patient waiting time at an emergency care center.
true
The "X" axis on a histogram represents the user specified ranges into which data are entered.
true
F distributions are used to compare __________________ .
variances