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48 Basics of DMAIC Quick Guide

APPENDIX 7

Explaining the 1.5 Sigma Shift

When the Six Sigma community talks about Six Sigma quality levels, they are
referring to a process operating at a quality level of 3.4 ppm. While a 6s
process theoretically operates at a quality level of 2 ppb, practitioners in the Six
Sigma community have found this to be unrealistic due to process drift. The
process location (measured by the mean) has reportedly been found to drift by
1.5s over long periods of time. This is referred to as long-term dynamic drift.

  3

Mean is Centered Cp=2.00 & Cpk=2.00

LSL USL

-8 -7 -6 -5 -4 -3 -2 -1  +1 +2 +3 +4 +5 +6 +7 +8

Defects: 0.001 Total Defects: 0.002 PPM Defects: 0.001
PPM PPM

To clarify what is meant by long-term dynamic drift, assume we start with a
process that has a Cp = 2.00 that is centered so that the Cpk = 2.00 as well. If it
drifts 1.5s, we will have a process with a Cpk = 1.50 while the Cp is still equals
2.00. That’s what operating at a Six Sigma quality level means.

  3

Mean is Shifted 1.5 Cp=2.00 but
LSL Cpk=1.50

USL

-9 -8 -7 -6 -5 -4 -3 -2 -1  +1 +2 +3 +4 +5 +6 +7

Defects: ~0 PPM Total Defects: 3.4 PPM Defects: 3.4 PPM

The mean will be 4.5s from one of the specification limits. The 3.4 ppm is the
worst case for this process when it has drifted the full 1.5s in either direction.

Graphics courtesy of Ken Kortge, Master Black Belt, Motorola.

Basics of DMAIC Quick Guide 49

APPENDIX 8

Glossary of Terms

1.5 Sigma Shift As it relates to Six Sigma, it is a ±1.5 standard deviation shift to the true-6-
5Ss sigma level to account for shifts in process location.
The general term for five Japanese words that relate to housekeeping, work
5-Whys place organization, clearing the work area, standardizing, and ingraining the on-
8-Discipline, 8-D going housekeeping effort into the culture of the organization.

Accuracy Asking “why” five times to tunnel into the root cause of a mistake.
Activity Plan
A structured approach of problem–solving that works through 8 disciplines:
Affinity Grouping Team Formation; Describe the Problem; Verify Interim Containment; Define &
ANOVA Verify Root Cause(s); Develop Solution(s); Implement Solution(s); Prevent
Recurrence; and Congratulate the Team!
Attribute Data Refers to the difference between the observed or measured value and the true
Bar Graph value.
Baseline An activity plan is an ordered list of the tasks that must be completed in order to
implement a solution or complete a project. An activity plan identifies what
Bell-Shaped Curve needs to be done, who needs to do it, and when it needs to be done by.
Benchmark Affinity grouping is a technique used to organize information. It can be used to
break a large problem or issue down into manageable chunks.
Best Practice ANOVA, or Analysis of Variance, is a statistical technique that helps to organize
Bimodal Distribution data and analyze the impact known changes in process variables have on the
output of the process
Black Belts
Data that can be counted, or classified, as go/no-go data.
Boundaries of
Freedom A type of graph used to compare data from two or more categories.

Brainstorming The beginning point; the starting point from which to measure progress of an
Brown Paper Flow improvement initiative.

Capable A pattern of variation known as the normal curve.

A source of best practices that becomes a target for performance levels.

A methodology or technique acknowledged to yield superior results.

A pattern of variation that has two or more peaks or modes. This is a sign of a
special cause of variation.
Subject matter experts in the use and application of a broad range of Six Sigma
tools; act as facilitators helping others use and learn to apply these tools to
improvement projects.

Clearly communicated limits for an individual or team demarcating the scope,
budgetary bounds, time line, and schedule constraints.

A group process used to generate ideas to solve a specific problem.

A visual flowcharting techniques in which actual forms and sample documents
are used to display the flow of the process or procedures on “brown (kraft)
paper.” The visual display aids in the identification of process simplification and
improvement ideas.
If the process is stable and the process spread is less than the customer’s
specification range (T.T.) with room to spare (industries today typically require
25%), the process is capable. Capable only means the process can fit within
the specification. However, it may not fall within the specification. Ideally we
want a process to be both capable and centered.

50 Basics of DMAIC Quick Guide

Capable and A process that is capable of meeting the specification and is operating in the
Centered approximate center of the specification; it has a Cp approximately equal to the
Cpk and the Cpk is equal to or greater than 1.33.
Cause & Effects A method of organizing the variables in a process by categories of people,
Analysis equipment, methods, materials, and environment to help us understand how
the variables create an effect on the process output.
Cause & Effects
Diagram A graphical representation of a cause & effects analysis.
CBT
The acronym for computer-based training; can include CD-ROM, LAN (local
Centerline area network), and web-based delivery formats.
The historical average of the characteristic the chart is monitoring. For a range
Champion
chart it would be the mean range for the process. For an X chart it, would be
Checklists the process mean. For a p Chart it would be the mean percent defective.
Common Cause In a Six Sigma initiative, a member of the Leadership Team who takes
ownership for the some aspect of the initiative and/or project, provides
Variation guidance, and removes obstacles and barriers of success.
Concentration
An ordered listing of what and when items are to be checked.
Diagram
Control Chart The variation in a process that is due to common causes or variables that are
always present in the process.
COQ
Correlation Analysis A type of data collection form that graphically shows the location and
concentration (or clustering) of defects and errors.
Cp
Tool used to help maintain statistical control of a process.
Cpk
COQ means the “Cost of Quality;” in reality it is a measure of the cost of poor
Cpl quality. The COQ is usually stated as a % of the cost of sales.
Cpm A statistical technique used to quantify the strength of association between two
Cpu variables, usually an input and an output.
Cr (or CR) The process capability index = T.T./6s. If the Cp is 1.0, the process is producing
exactly within the specification with no room to allow for process shifts. A Cp is
Critical Path like a bowling score - the higher the better.
CTC The Cpk is the best measure of process capability because it not only tells you if
CTQ the process is capable, but also whether it is centered. Cpk = minimum of {Cpu,
Cpl}. The Cpu measures the capability of the top half of the process and the Cpl
Current State Map measures the capability of the lower half of the process. The Cpk is like a
bowling score - the higher the better. In order for a process to be considered
capable, many companies require the Cpk must be at least 1.33.

The capability of the lower half of the process as measured against the LSL.

The capability of the process against both its specifications and its target.

The capability of the upper half of the process as measured against the USL.

The process capability ratio. The Cr tells us what portion of the specification the
process output takes up. The Cr does not tell us how well centered the process
is. The Cr is like a golf score - the lower the better. Cr = (6s/T.T.) x 100%
The critical path is the path on a PERT Chart from start to finish that takes the
longest time.
Critical to Customers; characteristics that are critical to the quality of the product
or service from the customer’s perspective
Critical to Quality; characteristics that are critical to the quality of the product or
service.
A current state map is a process mapping technique to define a process
including its inputs, outputs, and performance.

Basics of DMAIC Quick Guide 51

Design of A family of statistically based techniques and methods to conduct organized
Experiments (DOE) experimentation in order to obtain the maximum amount of information on a
process with the minimum time and the least cost expenditure.
Detection
DFE Identifying a problem or mistake after it has occurred.

DFM/DFA The acronym for design for environment; the environmental consideration of
designing a product or processing including recycleability, recycled content, and
DFMEA cradle-to-grave ownership issues.
The acronym for design for manufacturability and design for assembly; they are
DFSS related approaches to simplifying the product or process design to make it
easier to produce or easier to operate.
DFX The acronym for a Design-FMEA; an FMEA used to identify the potential risks
Dispersion associated with a (product) design.
The acronym for Design for Six Sigma, an approach used to design or re-
DMADV design a product or service from the ground up to meet Six Sigma performance.

DMAIC The acronym for a combined effort encompassing DFM, DFA, & DFE.

DOE Another term for variation in a process.
DPMO
Dynamic Control Acronym for Define, Measure, Analyze, Design, Validate; a model used to
Charts develop new products or processes or to reengineer an existing product or
process if the DMAIC method did not lead to adequate results.
EVOP Acronym for Define, Measure, Analyze, Improve, Control; a model used to
improve existing products or processes.
Failure Mode and
Effects Analysis The acronym for design of experiments.

Fault Tree Analysis Defects per Million Opportunities; a universal metric of process outputs.

Flowchart There are several specialized or dynamic control charts formats such as EWMA
FMEA (exponentially weighted moving average) and sloped control limit charts.
EWMA is often used for monitoring continuous processes. Sloped control chart
Forced Ranking formats are used to monitor processes with tool wear.
An on-line DOE technique used to slowly optimize the process output without
Fractional Factorial creating out-of-spec product.
Experiments An approach to identify which mistakes (failure modes) are the greatest
Frequency priorities to target for mistake-proofing. The prioritization is based on the effect
F-test of the failure mode, the frequency of occurrence of the root cause of the failure
mode, and the detection controls in place in the process.
Full Factorial A top-down determination of the events that can, at the root level, lead to a
Experiments failure or defect.
Future State Map
A graphical representation of the steps in a process.

See Failure Mode and Effects Analysis.

Forced ranking is a decision making tool that, like other voting and ranking
techniques, uses the team’s experience and knowledge to select an option or a
solution to a problem.
A DOE technique similar to Full Factorial Experiments. However we give up
some information between variables so that we can get results on the “main
factors” and some interactions with fewer experimental runs.

The number of times a value or event occurs.

Used to compare the variance of two populations when the population
parameters are unknown but can be estimated.
A DOE model that looks at each main variable (or factor) in the experimental
matrix and all of the possible interactions between variables. This technique
gives us a lot of information but could take a large number of experimental runs.
A view at what the process and its performance should look like in the future,
after an improvement initiative has been completed.

52 Basics of DMAIC Quick Guide

Gantt Chart Used to keep a project or a solution-implementation on schedule. The Gantt
chart shows relationships between tasks, when tasks need to be done, and can
GR&R Studies even show who needs to do a specific task.
Green Belts Conducted to determine if measurement systems are repeatable and
Hidden Plant reproducible.
Histogram Employees trained in using some of the Six Sigma tools so they can be active
In-Control participants on project teams.
A representation of the cost of quality. The hidden plant is the % of the plant
In-Specification working to produce ”poor” quality.
ISO 9000
A graph that shows the pattern of variation.
ISO/TS 16949
A process that is stable and with no special causes of variation present.
Interim Containment
IX Chart (or X Chart) A product or process or characteristic that falls within its specification limits.

JiT Defines a comprehensive approach to managing a quality system.

Kanban The harmonized supplier automotive quality system requirements document
LCL that, when coupled with customer-specific requirements, will satisfy QS-9000
(US), VDA 6.1 (German), AVSQ (Italian), and EAQF (French) Quality Systems.
Lean Thinking A temporary fix to a problem used while work to find the root cause of the
Leadership Team problem goes on leading to a permanent solution.

LSL A control chart of individual values.
Mean
Measurement An acronym for just-in-time; from a Six Sigma training standpoint, learners
System Analysis should receive training just before they will be applying the lessons learned, i.e.
just-in-time.
Measurement A kanban is a sign or signal. It is used to tell us when to produce or when to
Uncertainty replenish inventory.
MFMEA
Lower control limit of a control chart.
Mistake-Proofing
Mixture Experiments Lean thinking and Six Sigma are not different, they are complementary
philosophies. Lean tools focus on the reduction of waste of any kind.
Mode The senior management team that provides direction for the organization by
MR establishing the strategy and priorities.

Multivariate Analysis The lower limit of a specification.

The arithmetic average for a group of values. Also known as the X .
A study of the validity of the measurement system. If the measurement system
takes up more than 30% of the tolerance or more than 30% of the total process
variation, the measurement system can not be considered to be reliable and
must be improved or replaced.

See Type A Evaluation of Uncertainty and Type B Evaluation of Uncertainty.

The acronym for a Machine-FMEA; an FMEA used to identify the potential risks
associated with maintaining equipment so that is ready to run whenever
needed.
A family of techniques that make a process or product robust so that it cannot
fail. Also known as poka-yoke.
When experimenting with product formulations, standard DOE techniques don’t
work well. Mixture experiments give us a mechanism to overcome formulating
constraints

The peak in a distribution with the highest frequency of values or data points.

The “moving” range between two or more sequential samples or subgroups.

Multivariate analysis looks at any number of the input and output variables in a
process at the same time to identify unusual combinations of these variables.

Basics of DMAIC Quick Guide 53

Musts and Wants A structured approach for applying your decision criteria to solution options to
aid in selecting one option from many.
NGT An acronym for nominal group technique; NGT is a form of Voting and Ranking
and helps teams reach consensus decisions.
Nominal
Normal The value the customer ideally wants for a product parameter.
Distribution
One-Piece Flow A pattern of variation of a stable process in which the distribution looks like a
bell-shaped curve.
Opportunities
One-piece flow theoretically means flowing product though process steps in lot
Outlier sizes of one. With one-piece flow, processes are forced to simulate a
Out-of- continuous process; this increases responsiveness to customer needs and
Specification decreases waste.
Out-of-Control When calculating DPMO, the Total Opportunities are the number of CTQ
p Chart characteristics that could create a defect.

Pareto Analysis A point that falls outside of the normal distribution. A special cause of variation.

PDCA A product or process characteristic that falls outside of its specification.

PERT Chart A process that is not stable due to special causes of variation.

PFMEA A type of attribute control chart used to track the percentage of individual
components in a sample that are defective.
Pie Chart Organizing data from highest to lowest to ensure that we are working on the
area that has the greatest impact on us.
Poka Yoke The acronym for Plan-Do-Check-Act; the Deming improvement cycle. 8-D,
DMAIC, and DMADV are expansions on PDCA.
Population A project management tool that helps to determine the critical path for
Pp, Ppk completing a project or solution implementation as well as to plan the
deployment of resources
Project Management The acronym for a Process-FMEA; an FMEA used to identify the potential risks
Prevention associated with the operation of a process.
A data display technique. In a pie chart, the pie represents the whole and the
Preventive slices show how much of the whole each segment takes.
Maintenance, PM The Japanese term for mistake-proofing. Poka yoke is at the heart of the
Problem Statement Toyota Production System.

Problem- All of the output of a process.
Solving Process
Process performance indicators. Similar to Cp & Cpk. For Pp and Ppk, s is
Process calculated from all of the values in a sample. For Cp and Cpk, s is calculated
Capability using the range values from subgroups taken over a period of time.

A structured approach for keeping a project on-target, on-time, and on-budget.

Finding potential problems and correcting the problems before they cause
defects or mistakes.

Preplanned routine maintenance to prevent equipment failures.

A documented communication of the scope of the problem the team is assigned
to working. A complete Problem Statement should provide information relevant
to the problem to help the team get started and clarify what is expected from the
team.

A step-by-step problem-solving approach used by teams or individuals to get to
the root cause of a problem and then prevent its recurrence.

A measure used to determine if a process output is capable of meeting its
specification.

54 Basics of DMAIC Quick Guide

Process Also known as Cp. The process capability index = (T.T./6s). If the Cp is 1.0, the
Capability Index process is producing exactly within the specification with no room to allow for
process shifts. A Cp is like a bowling score - the higher the better.
Process Also known as Cr. The process capability ratio = (6s/T.T.) x 100%. The Cr tells
Capability Ratio us what portion of the specification the process output takes up. The Cr does
not tell us how well centered the process is. The Cr is like a golf score - the
Process Mapping lower the better.
Process mapping helps one understand a process by “drawing or mapping a
Pull System picture” of how it flows.
Pulling product through a process with kanban signals leads to a steady,
Push System predictable flow of product.
Pushing product through a process creates inventory “piles” after most process
QFD steps and especially before bottleneck operations.
QS-9000
See Quality Function Deployment.
Quality Function
Deployment Developed by U.S. automobile companies. Defines the quality system
R requirements for suppliers to the industry. Uses the ISO 9000 quality standard
R as a base and then adds to it. See ISO/TS 16949.
Range A structured technique that takes the voice of the customer (the customer
requirements) and translates that into the voice of the process (how the process
Reality Check should run to create the product the customer requires).

Recognition Range. A measure of the dispersion or variation in our data.

Regression Analysis The mean, or average, process dispersion.

Repeatability Also known as R. The highest value in a group of numbers minus the lowest
value in the same group. Describes the dispersion in our data.
Reproducibility A check of the practicality, feasibility, and cost-effectiveness of a mistake-
proofing solution.
Response Surface Acknowledging people’s contributions by sincerely thanking them in an
Analysis intangible manner. Recognition is different than a monetary reward.
Reward Used to compute the mathematical equation that defines the relationship
between two or more variables.
Root Cause Variation due to test equipment; i.e. variation in measurements found when the
Root Cause Analysis same appraiser uses the same measuring equipment to test the same
characteristic of the same sample.
s Variation in the average measurement made by different appraisers using the
Sample same measuring equipment measuring the same characteristic on the same
Scatter Diagram sample.

Screening An off-line DOE technique used to optimize the process output.
Experiments
Tangible compensation for completing a task or job.

The underlying reason a problem or mistake occurred.

Finding the true source of a problem, error, or mistake.

Sample standard deviation.

A representative subset of data randomly taken from a population of data.

Graphs of the relationship between two variables. They show graphically
whether a predictable relationship between the two variables does or does not
exist.
Extremely efficient experiments that look at “n” variables (or factors) in “n+1”
sets of experimental conditions (or treatment combinations). We are looking at
the effects of the variables on the process outputs.