Lean Six Sigma - Green Belt: Questions With Solutions
In Multi-Vari analysis, a graph is created that displays the possible sources of
variation affecting process output. Right Ans - True
The mean output of a process is the major factor in controlling that process
and ensuring that it meets process objectives. Right Ans - False
Both mean and standard deviation, a measure of variation, are important.
Some would argue that variation is more important than mean.
There is only one source of variation. Right Ans - False
There are two sources: common and special
The normal or expected cause of variation is called Common Cause. Right
Ans - True
Special cause variation is always present. No process can avoid it. Right
Ans - False
Common cause is always present.
Barring any accidents, the length of time it takes to commute to work is
subject to common cause variation. Right Ans - True
It is not possible to eliminate all common cause variation in most processes.
Right Ans - True
There is some variation in even the most carefully designed and controlled
processes.
Special cause variation is of most concern in Six-Sigma. It is unexpected and
can disrupt process output. Right Ans - True
Special cause variation represents the category of variation that effective Six
Sigma monitoring systems are expected to detect. Right Ans - True
,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. Right Ans - False
Normal variation is considered common cause variation.
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. Right Ans - 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with the flu and have been replaced by temporary help.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. Right Ans - 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. Right Ans - True
The longer is the vertical line in a Multi-Vari chart the lower is the "position"
variation. Right Ans - False
Multi-Vari charts also uncover why special cause variation occurs. Right
Ans - False
They only help expose the presence of special cause variation they cannot
determine its sources.
Multi-Vari charts also display output means. Right Ans - True
In a Multi-Vari chart, the range of variation is expressed along the "X" or
horizontal axis. Right Ans - False
The data within a vertical bar of a Multi-Vari chart is referred to as "within
variation" or "position variation." Right Ans - True
Multi-Vari Charts display the root cause of a problem Right Ans - False
This is not the purpose of a multi-vari chart
,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 Right Ans - True
A multi-vari analysis is visual and uses no statistics to compare output
variation. Right Ans - True
An organization wishes to determine if the variation across five processes is
different. A multi-vari analysis could be used. Right Ans - True
A SIPOC chart can be useful in identifying input variables for use in the Multi-
Vari chart Right Ans - True
The Pareto Principle states that _______ percent of the problem can be traced to
_______ percent of the possible causes. Right Ans - 80, 20
Multi-Vari charts can combine variables. One example is displaying the
relationship between call duration, location and time of day on the same chart.
Right Ans - True
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.
Right Ans - False
Common cause variation
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. Right Ans - True
Common Cause variation is predictable. Right Ans - True
Common cause variation represents variation from the target that can be
attributed to many random causes. It is predictable because random
variations will always occur. Special cause variation, on the other hand, is not
predictable and can be attributed to a special cause.
, 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. Right Ans - False
The focus of Six-Sigma is on Common Cause variation. Right Ans - False
The greater is the variation of data around the mean, the smaller will be the
standard deviation. Right Ans - False
The standard deviation represents the extent of variation in a distribution.
Right Ans - True
When the standard deviation is large, the spread of the data around a mean is
larger than if the standard deviation were small. Right Ans - True
Two statistics that define a normal distribution are the ________ and the
___________ . Right Ans - mean, standard deviation
The mean represents the centralness of a distribution Right Ans - True
Many distributions describing natural processes such as IQ (Intelligence
Quotient) or height can be classified as normal distributions. Right Ans -
True
In a normal distribution most of the data items cluster toward the ends or tails
of the distribution. Right Ans - False
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. Right Ans - 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. Right Ans - True
Ninety-five percent of the observations in a normal distribution fall above the
mean. Right Ans - False
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