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166 Cards in this Set
- Front
- Back
Six Sigma is:
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A customer focused well defined problem solving methodology supported by a handful of powerful analytical tools
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Continuous improvement is:
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Driven by execution of carefully selected projects.
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The goal of the Six Sigma approach is to:
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take small steps forward and no steps backward.
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The purpose of all six sigma work and all improvement efforts is to
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better serve customer needs and expectations thereby providing increasing value to the customer and ensuring repeat business.
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Six Sigma Approach
Uses statistics solely as |
tools for interpreting and clarifying data
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Six Sigma Approach
Requires not just statistics but changes in |
the culture of the organization.
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Six Sigma Approach
Requires a deep commitment from? |
the highest levels of management
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Six Sigma Approach
Requires a tolerance for endlessly questioning the |
validity of sacred company beliefs and the traditional ways "things are done around here"
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Six Sigma says the law of diminishing returns
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does not apply
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For Six Sigma to be effective what 3 things must happen?
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there must be a process in place
the processes must be brought into control statistically the processes must be improved (by reducing variation) "Six Sigma Mantra" |
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Six Sigma is:
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A customer focused well defined problem solving methodology supported by a handful of powerful analytical tools
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Continuous improvement is:
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Driven by execution of carefully selected projects.
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The goal of the Six Sigma approach is to:
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take small steps forward and no steps backward.
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The purpose of all six sigma work and all improvement efforts is to
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better serve customer needs and expectations thereby providing increasing value to the customer and ensuring repeat business.
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Six Sigma Approach
Uses statistics solely as |
tools for interpreting and clarifying data
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Six Sigma involves a series of steps designed to lead the organization through the gauntlet of process improvement. Major steps include:
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@DMAIIC
@D= Define @M= Measure @A=Analyze @I= Improve (cost justification) @I= Implement @C= Control (standardize and Validate) |
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D= Define the opportunity
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Improve on what matters most to the client and significantly impact the bottom line
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M= Measure the current performance
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Map the process gather initial performance data and determine current Sigma level.
Obtain client input factors critical to quality (CTQ) |
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A= Analyze the current process
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Perform cause and effect analysis to determine reasons for gaps in performance.
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I= Improve process efficieency
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Determine breakthroughs design future state: new process, new "sigma" level
Create dashboards, scorecards and plans |
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I= Implement improvements
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Execute plans, overcome barriers
Transition to the new process |
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C= Control and adjust new processes
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Measure improvements and breakthroughs
Report dashboard, scorecard data and client feedback |
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The study of variation begins with the teachings of
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Dr. Edward Deming... The theory of profound knowledge... essential for any organization that desired to be competitive in today's marketplace
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Profound knowledge is
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@Knowledge of systems
@Knowledge of Statistics (variations) @Knowledge of psychology (Motivation) |
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A system is
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a network of interdependent components that work together to try to accomplish an aim.
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Systems are
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managements responsibility.
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Managements job is to
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optimize the entire system over time.
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Variation happens it is
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the voice of the system or process
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Use statistics to make
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the invisible visible ...show patterns and types of variations
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Distinguish between
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special and common causes of variation
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Variation
Must act according to |
type of cause and avoid tampering.
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Shrink variation equals?
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reducing variation reduces costs
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Psychology
People want to |
do a good job and contribute and have pride and joy in their work
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Psychology
need to tap into |
intrinsic motivation
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Psychology
Must |
drive out fear and build trust.
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Everything does what
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Varies
nothing is exactly 100% repeatable. |
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About Variation
Special Cause |
find special causes and remove.
Those closest to the process are most likely to find the special causes of variations |
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About Variation
Common Cause |
Take action on the system
Management is responsible for the system |
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When only normal variation (common cause) is present in a process the process is said to
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be stable
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Stable processes are
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predictable
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Stable processes are in
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(statistical) control
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Stable processes have a
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known process capability
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A process is said to be in statistical control when
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through the use of past experience we can predict how the process will vary in the future. CONTROL = PREDICTABILITY
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CONTROL EQUALS
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PREDICTABILITY
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Theorem
Basic theorem of variation |
If you always do what you always done you will always get what you always got.
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Corollary to the Basic Theorem of Variation
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Insanity... always doing the same thing over and over again expecting a different result
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In order to monitor any process effectively there are several pieces of information that must be known:
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@ Central location
@ Spread @ Shape (bell shaped curve) @ Relationship of the variation to time |
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A Histogram is
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A graphical representation of data in a bar chart format.
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What is used to observe the "SHAPE" of the data?
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Histograms
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Central location
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@Mean
@Median @Mode |
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Variability
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@Range
@Standard Deviation @Shape |
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Measures of Central Location
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@Average
@Mode @Median @Arithmetic Mean |
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The Average is
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the expected value or the balance point
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Mode is
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the most frequently occurring value
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Median is the
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middle value
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Arithmetic Mean is
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the total of the individual values divided by the number of individual values.
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-
x |
Represents the symbol for average.
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If the shape of the distribution is not symmetrical use what
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median of the mode
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if the shape of the distribution is symmetrical use
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arithmetic mean
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6,7,7,8,8,8,9,9,9,9,10,10,11,11,12,13
The mode is? |
9 because it is the most frequently occurring value.
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6,7,7,8,8,8,9,9,9,9,10,10,11,11,12,13
The median is? |
9 because it is the middle value
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6,7,7,8,8,8,9,9,9,9,10,10,11,11,12,13
The mean is? |
9.1875 because it is the actual average.
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Measures of Variability are
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Range
Standard deviation |
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The range is
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the difference between the largest and the smallest values in the sample.
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The symbol for range is
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R
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Standard Deviation is
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a mathematical measure of the variability of the data about the mean.
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The symbol for Standard Deviation is
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S
6 |
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Between plus and minus one standard deviation of the mean we normally expect to find about what % of the values
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68%
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With in 2 standard deviations of the mean we would expect to find approximately what % of the values
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95.5%
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Within 3 standard deviations of the mean we would expect to find about what % of the values?
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99.73%
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3 standard deviations 99.73% of the values, represent what?
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virtually all the values and the expected limits of common cause variation necessary for a stable and predictable process
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Six Sigma Quality
Customer requirements are ? |
6 standard deviations from the mean in either direction.
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3 sigma equals ? errors per million
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27 errors per million
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6 sigma equals ? errors per million?
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3.4 errors per million
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six sigma total range is ?
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12 which means 6 standard deviations each side of the mean.
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The Grand Average
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is the process average. it is usually the average of the sample averages. (as long as all samples are the same size)
It is also the averge of all the individuals. |
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The symbol for grand average is?
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_
_ x |
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Calculate the grand average for
@2,3,6,9,1 @3,6,4,1,11 @2,7,22,0,9 @-4,8,0,14,0 |
@2,3,6,9,1....4.2
@3,6,4,1,11...5 @2,7,22,0,9...8 @-4,8,0,14,0...3.6 @20.8/4=5.2 |
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Average Range is the ?
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estimate for total process variability.
The average range is the average of the sample ranges |
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the symbol for average range is?
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_
R |
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The Grand Average
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is the process average. it is usually the average of the sample averages. (as long as all samples are the same size)
It is also the averge of all the individuals. |
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The symbol for grand average is?
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_
_ x |
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Calculate the grand average for
2,3,6,9,1 3,6,4,1,11 2,7,22,0,9 -4,8,0,14,0 |
2,3,6,9,1....4.2
3,6,4,1,11...5 2,7,22,0,9...8 -4,8,0,14,0...3.6 20.8/4=5.2 |
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Average Range is the ?
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estimate for total process variability.
The average range is the average of the sample ranges |
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the symbol for average range is?
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_
R |
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The Grand Average
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is the process average. it is usually the average of the sample averages. (as long as all samples are the same size)
It is also the averge of all the individuals. |
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The symbol for grand average is?
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_
_ x |
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Calculate the grand average for
2,3,6,9,1 3,6,4,1,11 2,7,22,0,9 -4,8,0,14,0 |
2,3,6,9,1....4.2
3,6,4,1,11...5 2,7,22,0,9...8 -4,8,0,14,0...3.6 20.8/4=5.2 |
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Average Range is the ?
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estimate for total process variability.
The average range is the average of the sample ranges |
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the symbol for average range is?
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_
R |
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Calculate R bar for the following data:
2,3,6,9,1 3,6,4,1,11 2,7,22,0,9 -4,8,0,14,0 |
2,3,6,9,1-------8
3,6,4,1,11------10 2,7,22,0,9------22 -4,8,0,14,0-----18 --------------------58/4=14.5 |
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Data is described to assist with the analysis in six sigma. in order to completely describe data we need to know the following?
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Location (Histogram/ranges)
Spread (Histogram/ranges) Shape (Histogram/ranges) Variation over time (off the control chart) |
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Most measures have ?
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Targets. for example an organization may promise delivery in 24 hours.
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A histogram shows us the ? of distribution
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shape. bell shape or normal curve
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Sometimes the shape is not normal what must we do?
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we must compare our shape with the expected shape to see if the process is behaving like it always has.
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Use the Histogram to compare the
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observed shape compared to the expected shape
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If the Histogram pattern is different from what we expect then?
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we may not be doing what we always have. or we may not be predictable or we may not be stable.
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Process monitoring is performed to
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determine the type and amount of variation that is present in a process as time goes by
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The two types of variation are
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common cause
& Special Cause |
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Control Charts are
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Statistical tools which shows the amount and type of variation present in any process that is being monitored.
and describe the representative nature of a stable, predictable, in a control process |
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Control chart shows how much?
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variation we have and what type of causes
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5 Components of control charts are:
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UCL upper control limit
LCL lower control limit CL Center line (shows where the character istic average falls USL Upper specification limit or upper customr requirement (come from customer) LSL Lower specification or lower customer reuirement. |
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UCL
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upper control limit
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LCL
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lower control limit
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CL
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Center line (shows where the characteristic average falls
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USL
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Upper specification limit or upper customer requirement (come from customer)
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LSL
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Lower specification Limit or lower customer requirement.
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Control limits describe the
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representative nature of a stable process. specifically control limits identify the expected limits of normal, random or chance variation that is present in the process being monitored.
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Control limits are set by
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the process. The process sets the limits itself. the only way to change control limits is by changing process.
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Specification Limits are those limits that describe what?
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the characteristics the product (or process) must have in order to conform to customer requirements or to perform properly in the next operation
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Specific limits come from
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directly from the customer
*what the product or process that may be to keep the customer happy *easy to change |
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Control limits different types of charts come in two categories
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Variables & Attributes
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Control limits different types of charts.
Variables |
* Averages and ranges, Green Belts are expected to be able to construct and interpret this control chart
* individuals and Moving ranges. This is useful in service applications * Averages and standard Deviations * Medians and Ranges |
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Control limits different types of charts.
Attributes (Things we count)... |
*Percent Defective
*Number Defective *Number of defects *Defects per unit |
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Constructing an Xbar and Rbar chart
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Identify characteristic and sampling scheme
Record Data Calculate sample average and sample range Calculate grand average and average range If stable (histogram of individual measurements) calculate limits Calculate control limits Construct control charts Plot initial data points Interpret chart with respect to variation common cause special cause. |
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What is needed for a sampling scheme (3)
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Determine sample size
sampling frequency (how often do we measure) Make sure we have a big enough sampling to be representative |
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Charts do what?
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Monitor processes and provide a record of behavior over time.
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When out of control it means
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not stable
special cause variation is present Stop and identify the special cause |
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Control limits describe what?
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the representative nature of a stable process. Specifically they identify the expected limits of normal, random or chance variation that is present in the process being monitored.
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Process Capability is ?
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the measured, inherent reproducibility of the product turned out by the process.
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Process capability can be quantified from what?
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data which in turn are the results for measurements of work performed by the process. It defines limits we would normally expect virtually all individuals to fall within.
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By definition a capable process is operating at?
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3 sigma level or 99.73%
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Process capability is the range
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over which the natural variation of a process occurs as determined by the system of common causes.
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Process capability it is the ability of
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the combination of people, machines, methods, materials and measurements to produce a product or service that will consistently meet design specifications.
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Process capability is measured by
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the proportion o output that can e produced within design specifications.
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Process capability is a measure of the uniformity of
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the process
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Process Capability can be measured only
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if all special causes have been eliminated and the process is in a state of statistical control.
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If process is not in control
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don't estimate its capability, its meaningless.
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Components of Process Capability are?
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Design specifications
Centering of natural variation Range or spread of variation |
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Capability measures...Short term show the
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capability oat a specific instance in time e.g.5 out of 90 samples did not meet customer requirements
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Capability measures .... Long term show
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the expected capability of the process based on the statistical projections using inherent process variability
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What must be performed prior to calculating any process capability measures?
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Histogram
& Control Chart |
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Greenbelts are expected to be able to calculate
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Percent or Proportion Non Conforming
Cp Index Cpk Index |
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Percent or proportion Non Conforming tells us what?
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once we know this we know defects/million
known sigma level |
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Cp Index and Cpk Index are what
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quality metrics ... a quick way to tell how we are doing relative to how we should be doing
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Percent Non Conforming reflects what
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the proportion of the population that we normally expect not to meet the process specifications.
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Percent Non Conforming corresponds to
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the tail areas on the normal curve sketch
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Capability Indices show the relationship
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between the process capability and the process specifications
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Cp measures
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potential capability assuming that the process average is equal to the midpoint of the specification limits and the processes operating in statistical control.
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Cpk reflects the
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current process mean's proximity to either specification limit. (when the process is centered Cp = Cpk) Although the indices are calculated differently the interpretation is the same. always use Cpk
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If Cpk is less than 1
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we are not capable
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if Cpk is equal to 1
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then equivalent to 3 sigma level and therefore capable.
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If Cpk is greater than 1
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then we are more than capable
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Understand Who? and Understand What?
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Who your customers are and what you provide for them.
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W@hat distinguishes Six Sigma from the other Quality Improvement Methods?
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Justifying improvements int eh language of management.
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D in DMAIIC IS
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Define. the hardest part of DMAIIC.
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D in DMAIIC means what
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Define
it includes identifying the problem, and setting the scope. It also includes: Identifying the customers and what is important to them Determining the outputs Determining the inputs Determining what is critical |
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Tools used in Defining are
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Process Analysis
Flow Charting Check Sheets Pareto Analysis Cause and ?Effect Diagrams FMEA(Failure Mode Effects Analysis) |
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The second step in DMAIIC is
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M for Measure.
Identify and verify critical quality characteristics Estimate current capability Determine where you are relative to desired objectives |
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Common tools used to measure
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Process Capability (Percent Nonconforming, Capability Indices)
Measurement Systems Analysis Cost of Quality (Appraisal, Detection, Failure) |
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Third Step in DMAIIC is
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Analyze
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Analyze does what
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makes sense out of the data that is collected during measure.
This shows the amount of improvement that might be possible to make the critical quality characteristic "best in class" |
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Possible Analysis tools are
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Descriptive Statistics
Inferential Statistics Probability FMEA prioritize potential failures according to their risk and drives actions to eliminate or reduce their likelihood of occurrence |
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Improvement
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in order to improve, possible improvements are evaluated in a logical and planned fashion
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Improvement tools
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Design of experiments (ANOVA, Factorial)
Simulation Cost Justification FMEA Project Management Correlation Regression (linear, Multivariate) |
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Implement means
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Improvements are implemented in a logical and planned fashion
a project plan is developed and managed. |
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C stands for
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Control
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In the control phase
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measures have been implemented and steps are taken to make sure improvements are maintained.
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Tools for control are
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Statistical process control cost of Quality
Cost Analysis ISO 9000 |
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Implementation Strategy items
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Top Management Support and Participation
Project Identification Resource Allocation Data Based Decision Making Measurement and feedback |
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Implementation process of Six Sigma must be
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Top down approach.
Responsibility must lie with senior management. Senior management must drive the process through the organization. Elements of this include selection of projects allocation of resources and decisions based on measurements |
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Steering committee
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Identifies projects
Identifies black belts allocates resources monitors progress reviews effectiveness establish implementation strategy and policies |
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Cost is the
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sum of the labor raw materials and overhead used to produce it. The minimum cost required to accomplish the functions desired is necessary cost and cost above this is unnecessary
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Variable cost is directly
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associated with the production of a product: direct labor direct materials
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Fixed costs is
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not affected by a change in level of production.
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Break Even Point
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Point at which total costs equals total revenue.
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