I am very pleased that this book has made it to a fourth edition, and am grateful to all of you who have adopted it over the past 12 years. This book is rare in that it spans two distinct markets: business and engineering. A previous survey revealed that adoptions are split almost evenly between the two areas, with about two-thirds of the units in schools of business. Keeping in mind the findings of this survey, and responding to both general market demands as well as specific reviewer suggestions, I have made several key changes to the Fourth Edition of Production and Operations Analysis that I believe have improved the book considerably. These changes include:

• The addition of a new chapter on supply chain management

• Enhanced international examples

• A stronger and simpler strategic framework, outlined in Chapter 1

• Increased and enhanced use and integration of Excel spreadsheets

• Selective updating and replacement of "Snapshot Applications" boxes

While the Fourth Edition is still 12 chapters, they are not the same chapters that were in the first three editions. The fourth edition is the first to have a new chapter and also the first to have a chapter eliminated. Chapter 6 on Supply Chain Management is new. It follows the style of other chapters in being a mix of quantitative and qualitative material. The chapter does include some material from the third edition that appeared in Chapters 1, 7, and 12,  but is mostly new. Chapter 12 from previous editions, "Recent Advances in Operations Planning and Control," has been eliminated. What were recent advances in 1989 are no longer so, and I was concerned that much of the material in this chapter was being ignored because it was separated from the core topics. I indicate below where some of the material formerly in Chapter 12 now appears.

A more coherent treatment of operations strategy is provided in Chapter I. Section 1.2 "Framework for Operations Strategy," is new. The Snapshot application featuring Wal-Mart has been moved to the new Supply Chain chapter, as was the other supply chain material that was formerly part of Chapter 1 .A new Snapshot Application on Read-Rite's strategic alliance with Sumitomo Metals now appears in this chapter in the section on global operations. Most of the remainder of the chapter has remained intact. Chapters 2-5 are largely unchanged. The linear programming supplement after Chapter 3 has been updated to reflect the fact the Excel's Solver is now the standard for spreadsheet based-linear programming.

Chapter 6 is the new chapter on Supply Chain Management. This chapter was placed here because of its conceptual tie with inventory management, the topic of the two previous chapters. Most of this chapter is new and provides, I believe, one of the most comprehensive treatments of supply chain management in operations texts. The chapter starts with the Wal-Mart Snapshot Application, followed by a comprehensive treatment of the transportation and trans-shipment problems. This section includes a new Snapshot Application on the successful multiechelon inventory model developed for IBM's spare parts management. This next section on DRP is new. Section 6 on vehicle routing formerly appeared in Chapter 7. Section 7 on product design incorporates some material from the Third Edition and some new material. The Snapshot Application on Dell Computer featured in this section is new. Section 8 on the role of information in the supply chain is mostly drawn from the Third Edition. Sections 9 (multilevel distribution systems) and 10 (global issues) are new. Section 10 also features a new Snapshot Application on the work done for DEC in the 1990s (prior their acquisition by Compaq).

Chapters 7-12 are the former Chapters 6-11 respectively. The material from the old Chapter 12 on flexible manufacturing systems is now part of Chapter 10, and the material from the old Chapter 12 on design for manufacturability is now in Chapter 11. The chapter on reliability and maintenance is now the final chapter, and remains essentially unchanged from the last edition.

There are many people to thank for their help with this edition. First, I am grateful to the reviewers retained by the publisher who provided valuable feedback and suggestions for improvements. They include:

Chung Lee - Texas A&M University

Ted Lloyd - Eastern Kentucky University

Joe Milner -Washington University

Izzet Sahin - University of Wisconsin @ Milwaukee

William Sherrard - San Diego State University

Sridhar Tayur - Carnegie Mellon University

David Yao - Columbia University

I continue to be indebted to colleagues at Santa Clara University—Chuck Feinstein, Rhonda Righter, Steve Smith, and Andy Tsay—and to the reviewers of previous editions,  whose comments and suggestions helped immeasurably in the early stages of this book's development. They include Nicholas G. Hall (Ohio State University), Arie Harel, John Hebert (University of Akron), Michael Kim (University of California @ Riverside), Hau Lee (Stanford University), Binshan Lin (Louisiana State University @ Shreveport), John Loucks (Bowling Green State University), Sanjay Mehrotra (Northwestern University), Kamran Moizadeh (University of Washington), Eddy Patuwo (Kent State University), Jayant Rjgopal (University of Pittsburgh), Larry Robinson, Meir Rosenblatt, Linus Schrage (University of Chicago), David Simchi-Levi (Massachusetts Institute of Technology), and Candace Yano (University of California @ Berkeley).

I would also like to thank the team at McGraw-Hill/Irwin for their help throughout this project. They include Sponsoring Editor Scott lsenberg; Developmental Editor, Christina Sanders; Marketing Manager, Zina Craft; Project Manager, Kimberly Hooker; Designer, Kiera Cunningham; Production Manager, Michael McCormick; Supplements Coordinator, Cathy Tepper; and New Media Producer, Ed Przyzycki. I am especially grateful to you, the users, who have continued to make this book a success. Many of you made suggestions and all of them have been carefully considered in this revision. Please feel free to let me know via email (snahmias@scu.edu) your opinion of the Fourth Edition. Finally, special thanks to my wife Vivian for her continued encouragement and support.