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The Certified Six Sigma Yellow Belt Handbook
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Also available from ASQ Quality Press: The Certified Six Sigma Green Belt Handbook, Second Edition Roderick A. Munro, Govindarajan Ramu, and Daniel J. Zrymiak The Certified Six Sigma Black Belt Handbook, Third Edition T.M. Kubiak and Donald W. Benbow Practical Engineering, Process, and Reliability Statistics Mark Allen Durivage The ASQ Pocket Guide for the Certified Six Sigma Black Belt T.M. Kubiak Process Improvement Using Six Sigma: A DMAIC Guide Rama Shankar Statistics for Six Sigma Black Belts Matthew Barsalou The ASQ Pocket Guide to Statistics for Six Sigma Black Belts Matthew Barsalou The Certified Six Sigma Master Black Belt Handbook T.M. Kubiak The Certified Quality Engineer Handbook, Third Edition Connie M. Borror, editor The Quality Toolbox, Second Edition Nancy R. Tague Root Cause Analysis: Simplified Tools and Techniques, Second Edition Bjørn Andersen and Tom Fagerhaug The Certified Manager of Quality/Organizational Excellence Handbook, Fourth Edition Russell T. Westcott, editor The ASQ Quality Improvement Pocket Guide: Basic History, Concepts, Tools, and Relationships Grace L. Duffy, editor To request a complimentary catalog of ASQ Quality Press publications, call 800-248-1946, or visit our website at http://www.asq.org/quality-press.
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The Certified Six Sigma Yellow Belt Handbook
ASQ Quality Press Milwaukee, Wisconsin
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American Society for Quality, Quality Press, Milwaukee 53203 © 2017 by ASQ. Printed in 2016 All rights reserved. Printed in the United States of America 5 4 3 2 1 21 20 19 18 17 16 Library of Congress Cataloging-in-Publication Data Names: Ramu, Govindarajan, author. Title: The certified Six Sigma yellow belt handbook / Govindarajan Ramu. Description: Milwaukee : ASQ Quality Press, 2016. | Includes bibliographical references and index. Identifiers: LCCN 2016022355 | ISBN 9780873899345 (hardcover : alk. paper) Subjects: LCSH: Six sigma (Quality control standard)—Handbooks, manuals, etc. | Production management--Handbooks, manuals, etc. | Quality control—Statistical methods—Handbooks, manuals, etc Classification: LCC TS156.17.S59 R36 2016 | DDC 658.5/620218—dc23 LC record available at https://lccn.loc.gov/2016022355 No part of this book may be reproduced in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Publisher: Seiche Sanders Acquisitions Editor: Matt Meinholz Managing Editor: Paul Daniel O’Mara Production Administrator: Randall Benson ASQ Mission: The American Society for Quality advances individual, organizational, and community excellence worldwide through learning, quality improvement, and knowledge exchange. Attention Bookstores, Wholesalers, Schools, and Corporations: ASQ Quality Press books, video, audio, and software are available at quantity discounts with bulk purchases for business, educational, or instructional use. For information, please contact ASQ Quality Press at 800-248-1946, or write to ASQ Quality Press, P.O. Box 3005, Milwaukee, WI 53201–3005. To place orders or to request a free copy of the ASQ Quality Press Publications Catalog, visit our website at http://www.asq.org/quality-press. Printed on acid-free paper
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I thank my mom, Vasantha, for her unconditional love and encouragement. My dad, Ramu, would have been so proud to see this book come out. The morals and principles that he taught me keep me grounded. Thanks to my wife, Anitha, and my children, Vibha and Vivek, for their patience and sacrifice of countless evenings and weekends. Without their support, this book would not have been possible.
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Table of Contents
List of Figures and Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CD-ROM Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction: The ASQ Certification Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xi xv xvii xix xxi
Part I Six Sigma Fundamentals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 1 A. Six Sigma Foundations and Principles . . . . . . . . . . . . . . . . . . . . . . Purpose of Six Sigma: Reducing Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methodology (DMAIC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Evolution of Six Sigma from Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Value of Six Sigma to the Organization as a Whole. . . . . . . . . . . . . . . . . . . . . . .
Chapter 2 B. Lean Foundations and Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . Purpose of Lean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lean Methodologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Value of Lean to the Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3 C. Six Sigma Roles and Responsibilities. . . . . . . . . . . . . . . . . . . . . . . 28 Chapter 4 D. Team Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Types of Teams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Stages of Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Decision-Making Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Communication Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 5 E. Quality Tools and Six Sigma Metrics. . . . . . . . . . . . . . . . . . . . . . . . 52 1. Quality Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 2. Six Sigma Metrics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Part II Define Phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Chapter 6 A. Project Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Voice of the Customer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Project Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Stakeholder Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Process Inputs and Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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viii Table of Contents Chapter 7 B. Project Management (PM) Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Project Charter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Communication Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Project Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Project Management Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Phase Reviews. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79 79 81 82 83 88
Part III Measure Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Chapter 8 A. Basic Statistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Chapter 9 B. Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Data Collection Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Qualitative and Quantitative Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Data Collection Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 10 C. Measurement System Analysis (MSA) . . . . . . . . . . . . . . . . . . . . . 104 1. MSA Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 2. Gauge Repeatability & Reproducibility (GR&R) . . . . . . . . . . . . . . . . . . . . . . . 105
Part IV Analyze Phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Chapter 11 A. Process Analysis Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 1. Lean Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 2. Failure Mode and Effects Analysis (FMEA) . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Chapter 12 B. Root Cause Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Whys or Why-Why Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Process Mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Force Field Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Matrix Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
121 122 123 128 129
Chapter 13 C. Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 1. Basic Distribution Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 2. Common and Special Cause Variation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Chapter 14 D. Correlation and Regression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 1. Correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 2. Regression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Chapter 15 E. Hypothesis Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Part V Improve and Control Phases. . . . . . . . . . . . . . . . . . . . . . . . . 157 Chapter 16 A. Improvement Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Kaizen and Kaizen Blitz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Plan-Do-Check-Act (PDCA) Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Cost-Benefit Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
158 158 160 163
Chapter 17 B. Control Tools and Documentation . . . . . . . . . . . . . . . . . . . . . . . . . 1. Control Plan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Control Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Document Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
168 168 173 178
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Table of Contents
Part VI Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 Appendix A ASQ Code of Ethics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 Appendix B ASQ Certified Six Sigma Yellow Belt (CSSYB) Body of Knowledge (2014). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 Appendix C ASQ BoK Comparison. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Appendix D Control Limit Formulas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 Appendix E Constants for Control Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 Appendix F Areas under Standard Normal Curve . . . . . . . . . . . . . . . . . . . . . . . . 197 Appendix G Binomial Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Appendix H Values of the t-Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Appendix I Acronym List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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235 263 267 269
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List of Figures and Tables
Part I Table 1.1
Mapping of PDCA with Six Sigma DMAIC model. . . . . . . . . . . . . . . . . . . . . . 4
Six Sigma tools overview by stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Approaches to quality over the years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Common symbols used in value stream mapping . . . . . . . . . . . . . . . . . . . . . . 15
Value stream map example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
The 5S cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5S workplace scan diagnostic checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
The 7S adaptation (Hirano). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Visual factory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Examples of mistake proofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
A sea of inventory often hides unresolved problems. . . . . . . . . . . . . . . . . . . . 25
C-shaped manufacturing cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Typical large Six Sigma organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Typical Six Sigma roles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Common negative team dynamics and potential countermeasures. . . . . . . . 39
Multivoting ranked approach example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Multivoting weighted approach example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Tools across DMAIC phases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Pareto chart of final assembly inspection defect codes. . . . . . . . . . . . . . . . . . . 54
Empty cause and effect diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Cause and effect diagram after a few steps of a brainstorming session. . . . . 55
High-level flowchart for an order-filling process . . . . . . . . . . . . . . . . . . . . . . . 56
Basic flowchart for replacement of a product under warranty. . . . . . . . . . . . 57
Run chart analysis (using statistical software). . . . . . . . . . . . . . . . . . . . . . . . . . 58
Example of a check sheet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Scatter diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 5.9 Figure 5.10
Histogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 – Example of X and R control chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Examples of metrics by Six Sigma stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Traditional quality cost curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
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List of Figures and Tables
Part II Figure 6.1
Map to the entries for the QFD matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Sequence of QFD matrices for product, part, and process planning . . . . . . . 69
Risk analysis table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
A format for SWOT analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Stakeholder analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Process diagram/model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Basic SIPOC diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Example of an activity network diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Example of an affinity diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Example of a prioritization matrix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Example of a relationship matrix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Example of a tree diagram showing a fault tree (used to study defects and failures). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Part III Figure 8.1 Example of a data set as illustrated by a frequency distribution, individual plot, histogram, and probability plot. . . . . . . . . . . . . . . . . . . . . . . . 94 Table 8.1
Summary of descriptive measures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Data collection plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Gage repeatability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Gage reproducibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Example GR&R analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
GR&R report using statistical software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Sources of measurement variation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Part IV Table 11.1
Value-added vs. non-value-added. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Steps in performing a design or process FMEA. . . . . . . . . . . . . . . . . . . . . . . . . 116
A typical risk action plan Gantt chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Example FMEA reporting and RPN chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
A typical top-level management review report for FMEA progress. . . . . . . . 119
Symbols commonly used in flowcharts and process maps. . . . . . . . . . . . . . . 124
Basic flowchart for replacement of a product under warranty. . . . . . . . . . . . 125
Cross-functional or swim lane flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Prioritization matrix example: determine the most suitable software package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Various populations and sampling distributions of the mean for selected sample sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Normal distribution (bell) curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Normal probability density function and cumulative density function . . . . 133
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List of Figures and Tables xiii
Sample versus population notations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Skewed distributions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Bimodal distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Formula, mean, and variance of certain distributions . . . . . . . . . . . . . . . . . . . 136
Binomial distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Binomial distribution using Microsoft Excel . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Average shifting, variation stable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Average stable, variation changing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 13.10 Average shifting, variation changing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Figure 13.11 Average stable, variation stable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Table 14.1
Examples of dependent and independent variables. . . . . . . . . . . . . . . . . . . . . 143
The four types of correlations in scatter plots . . . . . . . . . . . . . . . . . . . . . . . . . . 144
CORREL function in Microsoft Excel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Regression dialog box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Temperature viscosity experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Regression data analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Simple regression results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Error matrix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
One-tail test: (a) right-tailed test and (b) left-tailed test. . . . . . . . . . . . . . . . . . 152
Two-tail test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Power curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Part V Figure 16.1
Meaning of “kaizen.”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Shewhart cycle (1939). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Japanese PDCA cycle (1985). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Deming wheel (1950). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
PDSA cycle and model for improvement (1991, 1994) . . . . . . . . . . . . . . . . . . . 162
Cost of poor quality (COPQ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Modern quality cost curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
A sample control plan template. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
An example control plan—first page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Figure 17.3 Figure 17.4
An example control plan—second page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 – X and R control chart example with data plotted. . . . . . . . . . . . . . . . . . . . . . . 176
Example of a p-chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Change communication (manufacturing). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Change communication (service). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
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ASQ certification materials ASQ webinars History of quality Simulated exam—Note that these questions are not the questions that will appear on the exam. The sample questions are intended to represent the style of the exam questions and are offered for practice. Tools and templates Useful publications Worked out examples
*Please see the CD-ROM for a complete listing of the contents in each folder.
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elcome to The Certified Six Sigma Yellow Belt Handbook. This reference manual is designed to help both those interested in passing the certification exam of the American Society for Quality (ASQ) for the Six Sigma Yellow Belt and those who want a handy reference to the appropriate materials needed for successful Six Sigma projects. I have made a sincere attempt to make this book a reference for both beginners in Six Sigma and those who are already knowledgeable about process improvement and variation reduction. The primary layout of the handbook follows ASQ’s Body of Knowledge (BoK) for the Certified Six Sigma Yellow Belt (CSSYB) released in 2015. I have utilized feedback from Six Sigma practitioners and knowledge gained through helping others prepare for exams to create a handbook that I hope will be beneficial to anyone seeking to pass the ASQ CSSYB or other Six Sigma exams. In addition to the primary text, the handbook contains numerous appendixes, a comprehensive list of abbreviations, and practice exam questions; a CD-ROM accompanying the book contains additional materials. One caution—you are not allowed to take any of the exam questions from the CD-ROM or from any other simulation into the ASQ exam. While most ASQ certification exams use solely a multiple-choice question format (ASQ CMQOE and CSSMBB are exceptions), many users of ASQ handbooks on the academic side prefer essay-type questions for the chapters to test the comprehension of students using this book at colleges and universities. I would advise the ASQ exam takers to make a note of this but not be too concerned. The essay questions were added to challenge the users. The difficulty level of the essay questions is likely higher than that of the questions in the ASQ certification exam. Six Sigma trainers for organizations may find this additional feature useful, as they want their trainees (staff) to not only pass ASQ Six Sigma exams but have a comprehensive understanding of the Body of Knowledge that will allow them to support real Six Sigma projects in their roles. I intend to start an ASQ CSSYB handbook users group in LinkedIn (a w eb-based social media application for professionals) and would greatly appreciate readers’ comments and feedback on how the handbook can be improved. Constructive and respectful posts are encouraged. Users will be acknowledged if their input and feedback are found useful and incorporated into the next edition. I encourage users of the handbook to read the ASQ Quality Progress publication “Test Run” to obtain tips for passing the ASQ exam (http://asq.org/qualityprogress/2010/01/certification-asq/test-run.html and also located on this book's CD-ROM). xvii
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xviii Preface Test-takers will also find useful the CSSYB keyword search located on the CD-ROM. This lists the terms and phrases in the BoK and where they are located within the handbook, since in an open-book exam it is useful to the test-taker to be able to quickly find these within the book. It is recommended you print this out to use in conjunction with the handbook during the exam.
Where Are You in Your Career? Over the course of your professional career, you have learned to use many tools. Certification as a Six Sigma Yellow Belt is the beginning of your journey of achieving higher levels of accomplishments and potentially lifelong learning. Consider this as laying the foundation. The following career pyramid provides guidance on reaching additional certifications. It is not a representation of ASQ certification exam requirements or prerequisites; rather, it presents a logical order of how one would progress.
Level of accomplishment based on author's assessment
ASQ’s CMQ/OE, CSSMBB ASQ’s CQA, CHA, CBA, CSSBB, CPGP, CSQP, CQE, CRE, CSQE ASQ’s CSSGB, CCT, CQT
ASQ’s CSSYB, CQI, CQPA, CQIA
Best wishes as you embark on your Six Sigma journey!
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would like to thank the numerous individuals who have taught me technical and management acumen, and hard and soft skills; have provided opportunities for me; and have been coaches and mentors to me. I would like to acknowledge Noel Wilson from the ASQ Knowledge Center for her guidance and support of my publications since 2006. Noel is an asset to ASQ and a gift to quality professionals like me. We all learn a lot from our managers. Over my 30 years in quality management I have had lots of bosses and I have learned a lot about critical thinking. My very first manager taught me attention to details. Another manager explained to me that when my requirement is one, learn to live with half. Another one famously repeated “check, recheck, and cross check.” I learned to be empathetic to my colleagues and respectful to staff. While I was working at JDS Uniphase Corporation (JDSU), Peter Makin and Jordan Freed provided opportunities and support to strengthen my quality skills. Peter was so kind to offer me the opportunity to work for him and provided management visibility to my work. While I was working for Jordan, he continually encouraged me to pursue my ASQ certifications and provided necessary management support to formally launch my Six Sigma career. I am forever grateful to these individuals. Dan Courtney (formerly JDSU) provided guidance and mentoring during my early Six Sigma career. His decision to hire me in the JDSU Six Sigma organization was a great turning point for me. The hands-on experience of coaching and mentoring Black Belts and Green Belts, and setting up a global Design for Six Sigma program further strengthened my knowledge and experience. I would like to acknowledge the SunPower Corporation management team for its support of my continued professional development. I have always been fortunate to have managers who support my development. I would like to thank Quality Press staff Paul O’Mara and Matt Meinholz for their incredible patience, understanding, and support in this project, and John Noguera, CTO and cofounder of SigmaXL, Inc. I would also like to thank my coauthors from my previous publication on Six Sigma. I learned a lot working with Roderick Munro and Daniel Zrymiak on the second edition of The Certified Six Sigma Green Belt Handbook. Contents of that handbook provided a baseline for my authoring of The Certified Six Sigma Yellow Belt Handbook. I would like to thank the following Lean Six Sigma professionals who performed careful reviews at different stages of the book: S. Anilkumar, David S. Foxx, Eric Gemunder, and Chad Walters. Finally, there are many I am not addressing here. They all have my respect for their professionalism and continued support. xix
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Introduction: The ASQ Certification Process
his section contains information about the exam process itself. Although not part of the exam material, this is useful information to give you background and help you understand the ASQ Certification process. You are encouraged to read this section.
The Test Development Process Many exams, whether tests or certifications, are written by a very few people (sometimes only one person) based on what they think an examinee should know to meet the criteria of some training materials (like nearly all college exams). The American Society for Quality Control (ASQC changed its name to ASQ in 1997) started developing the Certified Quality Engineer (CQE) program in 1967, making it the oldest professional quality certification in the United States. ASQC gathered a small number of quality professionals together for the development cycle of the exam. The first CQE exam developers and a few others were grandfathered in, bypassing the taking of the first exam, which was offered in 1968. Throughout the 1970s and early 1980s ASQC and others developed more certification exams. During this time, the issue of what the difference is between a professional certification and a state license (for example, the Professional Engineers exam process) was being raised as some U.S. states and Canada started questioning the professional community about what they were doing. ASQC and other professional organizations started trying to distinguish certifications given by their organizations from state or other governmental certifications. Basically, one is granted by peer recognition (professional organizations), the other by a governmental licensing process. In response to this growing concern and the possibility of legal litigation as to the fairness of the exam process, ASQC wanted to become proactive about their certification process. After a benchmarking exercise and a search for what was considered the very best exam development process, ASQC partnered with the Educational Testing Service (ETS is the organization that creates and maintains the SAT exams for college-bound students). The two organizations worked together to develop an exam development process that would be legally defensible both in court and to the various governmental organizations who might choose to challenge the process. The ASQC CQE
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xxii Introduction exam was the first to be redesigned with the new development process. The basic steps include: • Design of a survey to identify the current tools and methodologies being used in a wide breadth of industries across the United States. • Targeting ASQ members who are currently certified in a particular discipline, as well as managers and industry leaders who are aware of the needs in the various industry sectors across the country. • Tabulating the results of the most widely used tools, techniques, and methodologies to create a basic Body of Knowledge (BoK) for the new or redeveloped exam. • Coordinating exam-writing workshops around the BoK, paying special attention to the demographics of the exam question writers. Each industry and all parts of the country are ensured some participation in the exam-writing process. • During the exam-writing process the participants are broken up into teams. Each person writes a few questions based on their assigned portion of the BoK and then has two or more other team members review the question for accuracy, references, and fairness. • The team leader submits the questions to the exam-writing workshop lead person, who also reviews the questions. Others will then review anything that raises any issue at the workshop. • The questions are then entered into a proposed exam bank based on their relevance to the specified exam’s BoK. • As enough questions are identified in the proposed exam bank, another workshop is called, with new reviewers to look over each question. The questions are accepted, reworked, or rejected for the BoK exam bank. • About six months before an exam is to be given, a sort of the exam bank is conducted to select a new exam (each exam is different from all other exams) with some alternate questions for each area of the BoK. This exam mockup is then presented to an exam review workshop. These participants review every question and discuss their attributes related to the BoK. At the end of this process the exam is set for the next offering. • Exams are prepared and distributed to testing centers or ASQ conferences where they will be administered to participants. • All exams are graded using the identified answers from the exam bank. Once all exams are graded, a statistical cut score is developed to maintain a predetermined level of ongoing knowledge for the BoK field of experience (this is not just a simple 70 percent or some other numerical pass score).
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The ASQ Certification Process xxiii • With the cut score established for a given exam sequence, all exams are then reviewed to determine those who passed. Any examinee that falls below the cut score will receive a Pareto diagram of their exam identifying where they had problems. Those that pass the exam will receive a certification and exam card for their wallet or purse. • Once an exam has been given, the exam questions are statistically reviewed for how well they discerned the knowledge of the applicants. Any questions that were generally missed or passed by a significant portion of the audience will be discarded. Only a very few of the questions will return to the exam bank for possible use on a future exam. • Every five years this cycle is repeated for each exam that ASQ offers. This process is long and tedious, and ASQ spends a lot of time, resources, and volunteer effort to maintain this process to ensure the highest level of professionalism possible for the certifications offered by the Society. Once you pass an exam, you are encouraged to join in this process to help ensure that future exams will be meaningful to the participants.
Ongoing Maintenance As can be seen in the previous section, ASQ maintains a comprehensive process for ensuring that exams are reviewed every five years and that the exams are of the highest professionalism possible. To this end, security is tight for the entire process, and very few individuals know the entire history of an exam question’s life to ensure that questions are not released to exam participants prior to an exam being given. Some of the general activities that ASQ uses to maintain exam processes are: • If you are a local section volunteer helping to administer a refresher program or teach a refresher course or other training process, you are not allowed to proctor an exam for the same BoK. • If you proctor an exam for a section or conference, you are not allowed to teach that BoK. • If you volunteer to assist with any of the activities listed in the previous section on the exam development cycle, you are not allowed to teach or publish anything related to that BoK. • ASQ maintains an ASQ National Certification Committee for each exam that is offered through the Society. Each exam is either coordinated through an ASQ division (based on their field of expertise) and/or the ASQ National Headquarters, who coordinates with all ASQ divisions that might have a stake in a specific exam. • These ASQ National Certification Committees are made up of ASQ member volunteers who meet on a regular basis to ensure that the processes listed above, the ASQ national activities, and other issues related to their specific exam are maintained at the highest possible
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xxiv Introduction level of professionalism. This includes recertification activities for those exams that have that requirement. • These ASQ National Certification Committees ensure that the process listed in the previous section is followed (usually by participating in and/or coordinating the various events) as well as ensure that the BoK is positioned for reevaluation every five years. After the questions have been used for a certain period of time, they will be put into an archival file with notes on each as to when it was used and statistical results of how the question performed on the exam. These old files can occasionally be used as a basis for writing new or variations of questions. Thus, it would be unlikely to see one of these questions show up on a future exam. While using practice exams (as included on the CD-ROM accompanying this handbook) for study can be useful, the user should realize that these are not the same questions that will be on the ASQ exam.
The Examination Process Given the aforementioned process, the ASQ exam candidate should realize that anyone saying that they have inside information as to what will be on any given exam is either violating the ASQ Code of Ethics (by stealing information, in which case ASQ will prosecute if found out) or stretching the truth in the way that they are presenting the information. The ASQ certification exam process is always evolving and will rarely ever have a question in the same format on any two given exams. The candidate must be prepared to answer questions that could be reasonably extracted from the ASQ Certified Six Sigma Yellow Belt BoK (see Appendix B). Also, given the number of various industries in the marketplace today, general questions can be asked about a given topic in any number of ways. One example, FMEA (note: acronyms are very rarely used in the actual exam). If you are in the automotive industry you might use the AIAG Potential Failure Mode and Effects Analysis (FMEA) Reference Manual, 4th edition (https://www.aiag.org/products/ products-list/product-details?ProductCode=FMEA-4) or the SAE J1739:2009 standard (http://standards.sae.org/j1739_200901/). On the other hand, if you are in the medical devices industry, you would have to use BS EN ISO 14971:2007 Medical devices—Application of risk management to medical devices (http://shop.bsigroup. com/ProductDetail/?pid=000000000030091423). Still other industries might use the book Failure Mode Effect Analysis: FMEA from Theory to Execution, Second Edition. Either way, any question related to FMEA might focus on what the primary function of FMEA is, which is to manage the risk of the product or service that your organization offers to a customer (either internal or external). So, you should not be shaken if a question sounds as if it comes from an industry other than the one in which you work. The point is whether you can decipher the intent of the question as it relates to the Yellow Belt BoK and answer the question using facts and reason. The sample questions on the CD-ROM have been selected from sample exam questions from ASQ Certification pages for you to use for practice. An effort was made to ensure that only the sample questions relevant to the CSSYB BoK were selected.
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The ASQ Certification Process xxv The ASQ Certified Six Sigma Yellow Belt Guidelines booklet starts off the explanation of the BoK with: Included in this body of knowledge (BoK) are explanations (subtext) and cognitive levels for each topic or subtopic in the test. These details will be used by the Examination Development Committee as guidelines for writing test questions and are designed to help candidates prepare for the exam by identifying specific content within each topic that can be tested. Except where specified, the subtext is not intended to limit the subject or be all-inclusive of what might be covered in an exam but is intended to clarify how topics are related to the role of the Certified Six Sigma Yellow Belt (CSSYB). The descriptor in parentheses at the end of each subtext entry refers to the highest cognitive level at which the topic will be tested. A complete description of cognitive levels is provided at the end of this document. After the BoK is listed, a description of the meanings of remember, understand, apply, analyze, evaluate, and create is given. This is important as it tells you the examinee what level of knowledge you will need for that category of the BoK. The ASQ booklet lists the levels of cognition as: Based on Bloom’s Taxonomy—Revised (2001) In addition to content specifics, the subtext for each topic in this BoK also indicates the intended complexity level of the test questions for that topic. These levels are based on “Levels of Cognition” and are presented below in rank order, from least complex to most complex. Remember (Knowledge Level) Recall or recognize terms, definitions, facts, ideas, materials, patterns, sequences, methods, principles, and so on. Understand (Comprehension Level) Read and understand descriptions, communications, reports, tables, diagrams, directions, regulations, and so on. Apply (Application Level) Know when and how to use ideas, procedures, methods, formulas, principles, theories, and so on. Analyze (Analysis Level) Break down information into its constituent parts and recognize their relationship to one another and how they are organized; identify sublevel factors or salient data from a complex scenario. Evaluate (Evaluation Level) Make judgments about the value of proposed ideas, solutions, and so on, by comparing the proposal to specific criteria or standards. Create (Synthesis Level) Put parts or elements together in such a way as to reveal a pattern or structure not clearly there before; identify which data or information from a complex set are appropriate to examine further or from which supported conclusions can be drawn.
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xxvi Introduction These words can be kept in mind while reviewing the chapters in this book to get a better sense of the detail of questions that could be asked in that section. This is also why it may appear that some material is covered in more than one section of the BoK. In preparing for the actual exam, we suggest that you do the following: • Follow the list of “What Can and Can Not Be Brought into the Exam Site” found on the ASQ certification website—Frequently Asked Questions—“Taking the Exam.” • Select the reference that you have used in preparing for the exam. You should be familiar with how the reference is laid out and how you will use it. • Create an index of your planned references—you are allowed to use self-prepared information as long as there are no practice exam questions in the material. • Consider having a good Standard English dictionary available. Sometimes a word might be used in the questions that you may not be familiar with. • Arrive at the exam site early so that you can set up your materials in a manner that best fits your needs. You might even call the chief proctor ahead of time to learn the room layout if you have not been to the particular exam site before. • Remember that anything that you write on during the exam (scratch paper, exam pages, answer sheets, and so on) must be turned in to the proctor at the end of the exam. Thus, during the exam do not write in any of your references that you want to take home with you. • Relax and breathe. Additional advice given in the ASQ Certified Six Sigma Yellow Belt brochure includes: Test takers are also advised to keep in mind these general pointers about standardized exams: • Read all of the questions on the first page of the test so you realize that you do know the material. In other words, relax. • Read each question thoroughly. Don’t assume you know what’s being asked. • Eliminate implausible answers and move quickly past the obviously wrong choices. • Keep in mind that an answer may be a correct statement in itself but may not answer the question. • Two answers may say exactly the opposite things or may be very similar. Read them again to decide what makes one correct and the other wrong. • ASQ does not subtract points for incorrect answers. Answer every question. There is no penalty for guessing, so you have a minimum 25 percent chance
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The ASQ Certification Process xxvii of getting it right, and even higher if you are successful in eliminating one or two of the answers as incorrect. • Go through and answer the questions you know. Then go through and read the ones you’re unsure of. • Mark those you are still uncomfortable with. You will narrow the field down to just a few questions you will need to spend more time on. These are the questions you might want to use your reference books for. • Be aware of the time available for the exam and the remaining time as you work through the exam. • Do not select more than one answer for a question. If you do, it will be scored as a “blank.” For example, you think that both A and C are correct answers. Select only one answer and use the comment sheet supplied with your test to point out why you think both A and C are correct. Your comments will be reviewed before results are reported. Taking an exam (offered by ASQ or any other organization) is a matter of preparation on the participant’s part, and your results will show how well you achieved the exam requirements. We have seen people who based on overall education should pass an exam not do well, and the other extreme where a person who we thought might struggle but studied very hard actually passed the exam. Study and use your reference materials, and know where and how to find information when you need it. Few people can memorize everything, so the next best thing is knowing how to find information quickly when needed so that you can finish the exam in a timely manner. The breadth and scope of material within this handbook is based on the current version of the ASQ BoK for Certified Six Sigma Yellow Belt practitioners. When reviewing the material, there are two considerations: c overage and intensity. Coverage reflects the material in relation to the expected scope of the exam. ASQ has defined for each BoK category the number of questions expected to be present on the exam. It is important to devote the appropriate time to each s ection in order to ensure proper preparation. Without considering the coverage of the BoK, there is a risk that certain portions will be inadequately addressed in advance of the exam. One practice is to create a matrix on a spreadsheet indicating the BoK items on one axis, and the study progress made for each item on the other. Maintaining such a matrix would clearly indicate those areas where mastery has been achieved, and where more effort is required. Intensity refers to the learning level specified by ASQ, as referenced by the Bloom’s Taxonomy category. Those topic areas with the highest knowledge levels require additional effort by the examinee to fully master the concepts to sufficiently select or derive the correct response on the exam. Consequently, more effort should be devoted to those BoK items with the highest levels of knowledge, as these will align with the most complicated and time-consuming questions on the exam. For convenience, those items with the highest levels have been included within the following table for extra attention.
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xxviii Introduction The components of the BoK are explained below with two examples. In the Yellow Belt BoK, only two levels of cognition are used: “Understand” and “Apply.” Section
I. Six Sigma Fundamentals
1. Types of teams
Identify the various types of teams that operate within an organization (i.e., continuous improvement, self-managed, and cross-functional) and their value. (Understand)
II. Define Phase
A. Project identification