Welcome to the exciting world of statistical process control! I am very pleased to write this book, as I have had passion for the subject for many years. I was first introduced to SPC over 25 years ago, as a graduate student intern at a leading computer products manufacturer. Although I had a bachelor's degree in engineering, and had worked for several years in industry, I had not been exposed to this particular type of statistical analysis. The manufacturing engineers I worked with had only limited experience, and together we persevered our way through implementing control charts on a key process. Along the way, we made what I later determined were several fundamental errors. We learned the hard way that our process suffered from issues that hadn't been discussed in our textbook examples.
I took these hard lessons back to graduate school and learned as much as I could on the techniques. I applied them myself as a quality director in a couple of manufacturing organizations. In the early 1990s, I had the chance to become the technical services director for a company that developed SPC software. In that capacity I oversaw the technical support group, working with customers as they implemented SPC in a wide variety of industries including healthcare, aviation, banking, insurance, chemical processing and manufacturing. Our customers had seemingly varied needs; in reality there were many common threads. As much as each industry felt theirs was unique, in fact they had much in common. As might be expected, the tools of SPC have application across many types of processes, with only subtle differences in use.
As I write these pages, I am now president and chief operating officer of the company. Over the past 20 years I have applied these tools internally to our key processes, to learn, improve, and predict the dynamics of our internal sales and support processes, as well as our marketing and product development efforts. SPC is an integral part of what we do, and how we remain competitive in a sometimes crowded market. It provides the fundamental backbone to our systems, to consistently meet the needs of a demanding yet appreciative audience of quality professionals. I am indebted to many of these clients, who over the years have shared their problems and experiences with me, through their technical support issues, sales inquiries or training sessions. I feel quite fortunate to have worked with so many professionals who work diligently to service their customers and seek the truth that only data can provide. I have tried to encapsulate as much of their collective experiences in this book as possible.
Examples are provided throughout this book from a wide variety of applications, including general service (or transactional) processes, healthcare process, chemical processing and manufacturing. The books' topics build on each other, so it is recommended to read each chapter in the order provided. There are a number of critical and fundamental concepts discussed in earlier chapters that are required for later chapters.
Calculations and statistical assumptions are provided as needed, with emphasis on chart application and interpretation. Examples are provided for each chart, which may be downloaded from the author's Web site at www.qualityamerica.com/downloads/SPCDemystified.htm. Given the commercial availability of inexpensive SPC software, students are expected to use statistical software to quickly calculate the statistics and draw the chart. A time-restricted license of an easy to use MS Excel add-on for SPC is available for free via the above link for users of this textbook. This commercially-available SPC software package has been confidently used by thousands of organizations worldwide to quickly perform SPC analysis.
This text may be used for training groups of SPC practitioners within an organization, or for self-study to master the tools and methodology of statistical process control.
I hope you enjoy it and have the opportunity to realize the full potential of these powerful tools.