Lean transformations are decidedly more challenging when the math is inconsistent with lean principles, misapplied, or just plain wrong. Math should never get in the way of a lean transformation, but instead should facilitate it. Lean Math is the indispensable reference for this very purpose. A single, comprehensive source, the book presents standard and specialized approaches to tackling the math required of lean and six sigma practitioners across all industries—seasoned and newly minted practitioners alike. Lean Math features more than 160 thoughtfully organized entries. Ten chapters cover system-oriented math, time, the “-ilities” (availability, repeatability, stability, etc.), work, inventory, performance metrics, basic math and hypothesis testing, measurement, experimentation, and more. Two appendices cover standard work for analyzing data and understanding and dealing with variation. Practitioners will quickly locate the precise entry(ies) that is relevant to the problem or continuous improvement opportunity at hand. Each entry not only provides background on the related lean principles, formulas, examples, figures, and tables, but also tips, cautions, cross-references to other associated entries, and the occasional “Gemba Tale” that shares real-world experiences. The book consistently encourages the practitioner to engage in math-assisted plan-do-check-act (PDCA) cycles, employing approaches that include simulation and “trystorming.” Lean Math truly transcends the “numbers” by reinforcing and refreshing lean thinking for the very purpose of Figuring to Improve. REVIEWER COMMENTS “Hamel and O’Connor provide both the novice and experienced lean practitioner a comprehensive, common-sense reference for lean math. For example, I know that our Lean Support Office team would have gladly used dozens of Lean Math entries during a recent lean management system pilot. The concepts, context, and examples would have certainly helped our execution and provided greater clarity during our training activities. Lean Math is a must have book for Lean Support Office people!” —Dave Pienta, Director, Lean Support Office, Moog, Inc. Aircraft Group “A practical math book may sound like an oxymoron, but Lean Math is both pragmatic and accessible. Hamel and O’Connor do an excellent job keeping the math as simple as possible, while bringing lean principles to the forefront of the discussion. The use of insurance and healthcare industry examples especially helps simplify the translation for lean practitioners in non-manufacturing industries. Readers will be able to use the numerous tables and figures to clearly illustrate and teach lean concepts to others. Lean Math is a reference book that every lean practitioner or Black Belt should have in their library!” —Peter Barnett, MBB, Liberty Management System Architect, Liberty Mutual Insurance “Lean Math is a comprehensive reference book within which the lean practitioner can quickly find straightforward examples illustrating how to perform almost any lean calculation. Equally useful, it imparts the importance of the relevant lean principal(s). While coaching some recent transformation efforts, I put Lean Math to the test by asking several novice practitioners to reference it during their work. They were promptly rewarded with deeper insight and effectiveness—a reflection of this book’s utility and value to the lean practitioner.” —Greg Lane, international lean transformation coach, speaker, and author of three books including, “Made-to-Order Lean: Excelling in a High-Mix, Low-Volume Environment” “While the technical, social, and management sciences behind lean must be learned by doing, their conceptual bases are absolutely validated by the math. This validation is particularly crucial to overcoming common blind spots ingrained by traditional practice. Hamel and O’Connor’s text is a comprehensive and readable resource for lean implementers at all levels who are seeking a deeper understanding of lean tools and systems. Clear diagrams and real-world examples create a bridge for readers between theory and practice—theory proven by practice. If math is the language of science, then Lean Math is indeed the language of lean science.” —Bruce Hamilton, President, Greater Boston Manufacturing Partnership, Director Emeritus for the Shingo Institute “Mark and Michael have done a tremendous service for the lean community by tackling this daunting subject. There are so many ways to quantify value, display improvement, and define complex problems that choosing the right methods and measures becomes an obstacle to progress. Lean Math helps remove that obstacle. Almost daily, operations leaders in every industry need the practical math and lean guidance in these pages. Now, finally, we have it in one place. Thank you.” —Zane Ferry, Executive Director, National Operations, QMS Continuous Improvement, Quest Diagnostics “Too many lean books dwell on principles, but offer little to address critical how-to questions, such as, ‘How do I use these concepts to solve my specific problem?’ With plain English explanations, simple illustrations, and examples across industries, Lean Math bridges a long-standing gap. Hamel and O’Connor’s Lean Math is sure to become a must-have reference for every lean practitioner working to improve performance in any modern workplace.” —Jeff Fuchs, Executive Director, Maryland World Class Consortia, Past Chairman, Lean Certification Oversight Committee “Lean Math fills a huge gap in the continuous improvement library, helping practitioners to translate data, activities, and ideas into meaningful information for effective experimentation and intelligent decisions. This reference comes at a critical time for the healthcare industry as we struggle to improve quality, while controlling costs. Though we don’t make widgets, our people, processes, and patients will benefit from the tools provided in this reference. The numerous examples, as well as the Gemba Tales scattered throughout the book, bring life to the principles and formulas. Lean Math is impressive in both scope and presentation of content.” —Tim Pettry, Senior Process Improvement Specialist, Cleveland Clinic “Lean Math is a great book for those times when only the correct answer will do. The math, along with the Gemba Tales, are helpful for those in the midst of the technical aspects of a transformation, as well as those of us who once knew much of this but haven’t used it in a while.” —Beau Keyte, organization transformation and performance improvement coach, author of two Shingo-Award winning books: “The Complete Lean Enterprise” and “Perfecting Patient Journeys” “Math and numbers aren’t exclusively the domain of six sigma! Toyota leaders describe lean as an organizational culture, a managerial approach, and a philosophy. They also maintain that the last piece of lean is technical methods, which includes the math we need for properly sizing inventory levels, validating hypotheses, gauging improvement, and more. Lean Math is a useful book that compiles important mathematical and quantitative methods that complement the people side of lean. Hamel and O’Connor are extremely qualified to deftly explain these methods. Lest you think it’s a dry math text, there are Gemba Tales and examples from multiple industries, including healthcare, which illustrate these approaches in very relatable ways.” —Mark Graban, Shingo-Award winning author, speaker, consultant, and blogger “When you begin a lean journey, it’s like starting an exercise regimen—the most important thing is to start. But as you mature, and as you achieve higher levels of excellence, rigor becomes increasingly important. Lean Math provides easy, elegant access to the necessary rigor required for effective measurement and analysis and does so in practical terms with excellent examples.” —Misael Cabrera, PE, Director, Arizona Department Environmental Quality