From the Back Cover

Most software-development groups have embarrassing records: By some accounts, more than half of all software projects are significantly late and over budget, and nearly a quarter of them are cancelled without ever being completed. Although developers recognize that unrealistic schedules, inadequate resources, and unstable requirements are often to blame for such failures, few know how to solve these problems. Fortunately, the Personal Software Process (PSP) provides a clear and proven solution. Comprising precise methods developed over many years by Watts S. Humphrey and the Software Engineering Institute (SEI), the PSP has successfully transformed work practices in a wide range of organizations and has already produced some striking results.

This book describes the PSP and is the definitive guide and reference for its latest iteration. PSP training focuses on the skills required by individual software engineers to improve their personal performance. Once learned and effectively applied, PSP-trained engineers are qualified to participate on a team using the Team Software Process (TSP), the methods for which are described in the final chapter of the book. The goal for both PSP and TSP is to give developers exactly what they need to deliver quality products on predictable schedules.

PSPSM: A Self-Improvement Process for Software Engineers presents a disciplined process for software engineers and anyone else involved in software development. This process includes defect management, comprehensive planning, and precise project tracking and reporting.

The book first scales down industrial software practices to fit the needs of the module-sized program development, then walks readers through a progressive sequence of practices that provide a sound foundation for large-scale software development. By doing the exercises in the book, and using the PSP methods described here to plan, evaluate, manage, and control the quality of your own work, you will be well prepared to apply those methods on ever larger and more critical projects.

Drawing on the author’s extensive experience helping organizations to achieve their development goals, and with the PSP benefits well illustrated, the book presents the process in carefully crafted steps. The first chapter describes overall principles and strategies. The next two explain how to follow a defined process, as well as how to gather and use the data required to manage a programming job. Several chapters then cover estimating and planning, followed by quality management and design. The last two chapters show how to put the PSP to work, and how to use it on a team project. A variety of support materials for the book, as described in the Preface, are available on the Web.

If you or your organization are looking for a way to improve your project success rate, the PSP could well be your answer.

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About the Author

Watts S. Humphrey is well known as the author of several influential books on the software development process and software process improvement. Humphrey is a fellow of the Software Engineering Institute (SEI) at Carnegie Mellon, where he founded the Software Process Program and provided the vision and early leadership for the original Capability Maturity Model (CMM). He also is the creator of the Personal Software Process (PSP) and Team Software Process (TSP), methods designed to improve the quality of work done by both individual developers and project teams. Most recently Humphrey was awarded the National Medal of Technology by President George W. Bush. This is the highest honor awarded by the president to America’s leading innovators.



Excerpt. © Reprinted by permission. All rights reserved.

The record of most development groups is poor, but the record of software groups is particularly bad. The Standish Group reports that more than half of all software projects are seriously late and over budget, and that nearly one-quarter of them are cancelled without being finished.1 Under 30% of the projects were considered successful. Most of the software developers I know are well aware of these problems and can even explain their causes: unrealistic schedules, inadequate resources, and unstable requirements. Although these problems are common and not hard to solve, few developers know how.

It is tempting to blame others for our difficulties, but a victimlike attitude doesn’t solve problems. When you approach these software management problems in the proper way, you can generally solve them. However, this requires skills and practices that you may not have learned. It also requires dealing with management on management’s terms. You can gain the required practices with the Personal Software Process (PSP).2 This book describes the PSP and explains the practices and methods you will need to deliver quality products on predictable schedules. After learning these skills, you will be qualified to participate on a team that uses the Team Software Process (TSP). Such teams are called self-directed because they define their own working practices and negotiate their plans and schedules with management. The final chapter of the book describes the TSP and how it helps to put you in charge of your own work.Being a Software Engineer

An engineer is someone who knows how to consistently and predictably do quality work. Many of the states in the United States have regulations governing the practice of engineering and they do not allow people to call themselves engineers unless they have demonstrated competence in their professional specialty. Most engineering fields were originally established because the public demanded protection from unqualified work, particularly in building construction, steam power plants, and the like. Without such licensing, steam boilers frequently exploded and bridges collapsed. Although licensing did not magically solve all of these problems, it has been a big help.

Licensed engineers use known and proven methods, they are tested to ensure that they consistently do quality work, and they are required to demonstrate their competence at producing safe products. The difference between a licensed engineer and any other technical worker is that the engineer knows the proper ways to do his or her job and is required by law to work that way regardless of management, customer, or other pressures.

If we are to call ourselves engineers, we must learn to produce quality products on predictable schedules. This requires that we learn how to consistently meet our commitments and that we know how to handle the normal challenges of creative development work. Software development is the most challenging professional occupation I know of and we must all consistently use the best available methods to meet our management’s and our customers’ needs. Quality Problems

Poor quality management causes many of today’s software problems. Most software professionals spend nearly half of their time testing and fixing their products during development and final testing. Poor quality also leads to schedule problems, with defective products delivered long after they were committed. Although fixing a few defects may seem inconvenient, even fairly small programs can have hundreds of defects, and finding and fixing them can take many weeks or even months. Software quality starts with the individual developer. If any of the program modules that we develop have numerous defects, they will be hard to test, take time to integrate into larger systems, and be troublesome for our users.

Most of us can be highly productive when writing very small programs. However, our productivity falls off sharply when we develop larger programs. Although developing bigger systems involves some added architectural and design work, most of the added effort is caused by defects. The average amount of time it takes to find and fix each defect increases exponentially as programs become larger. However, if you can consistently write high-quality module-size programs, you will produce better products and improve your and your organization’s productivity.

A disciplined software engineering process includes effective defect management, comprehensive planning, and precise project tracking and reporting. This book shows you how to use these disciplines to do better development work as an individual and as a TSP team member. It also shows why these practices are essential if you want to manage your own work.The Benefits of Being a Software Engineer

As our lives increasingly depend on software, the demands for safety, security, and quality will only increase. This means that the demand for capable software professionals will also increase. Unfortunately, few software developers have any way to distinguish themselves from the many programmers who bang out poor-quality code. With PSP training, you can apply to the Software Engineering Institute to become a PSP-certified software professional. This will distinguish you from the many developers who have no unique qualifications. PSP training will also qualify you to participate on a TSP team, and PSP certification will assure potential employers that you are a professional who is capable of producing high-quality software for predictable costs and on committed schedules. Other personal benefits of PSP certification are the added recognition of being a skilled software professional and easier access to more responsible and higher-paying positions. Developers with such qualifications are now widely sought and will be increasingly needed in the future.Who Should Learn the PSP?

Modern technical work involves many specialties, and the people who participate in developing modern products and systems now come from a wide range of disciplines. To produce quality products on predictable schedules, all of the work that these people do must be planned, managed, and quality-controlled. This means that just about everyone associated with system development must know how to do disciplined engineering work. It also means that just about anyone doing such work would benefit from learning the PSP.

Although the examples and exercises in this book concern developing small programs, this is only because, even for small programs, software development is a marvelously rich process that can be measured and analyzed. This makes the software process particularly suitable for teaching disciplined engineering practices. Most modern professionals in almost any technical field now learn to write programs during their education, so the PSP course is appropriate for almost anyone planning an engineering or technical career, and it is particularly appropriate for anyone planning to work in product or system development. The Approach Taken by This Book

With the growing importance of software and software products, organizations will increasingly need software engineers who consistently use disciplined personal practices. To meet this need, we must learn and consistently practice these disciplines with every program we write. If we don’t use sound development practices when writing module-size programs, there is little chance that we will use them when writing large programs.

When students start to program, they generally begin by learning a programming language. They practice on toy problems and develop the personal skills to deal with issues at this toy level. As they take more courses, they build their personal skills and can soon develop fairly large programs relatively quickly. These programming-in-the-small skills, however, are inherently limited. Although they may suffice on small-scale individual tasks, they do not provide an adequate foundation for solving the problems of large-scale, multiperson, distributed project teams.

This book follows a fundamentally different strategy. It scales down industrial software practices to fit the needs of module-size program development. It then walks you through a progressive sequence of software processes that provide a sound foundation for large-scale software development. By doing the exercises and using the methods described in this book, you will learn how to use the methods for yourself. Once you have learned and used these practices on module-size programs, you will have the skills to use them on larger projects. Although some additional requirements, design, implementation, and testing methods are needed for developing large programs, the basic software engineering disciplines taught by this book apply directly to large-scale system development. The reason, of course, is that large systems are built from collections of program modules that are much like the programs you develop in the PSP course.

The principal goal of this book is to guide you in developing the personal software engineering skills that you need to perform at your very best. Consider the challenge of improving personal performance. In sports, for example, runners know the length of the track, their personal time, their fastest time, and the record time for each event. With proper coaching and guidance, they learn their personal strengths and weaknesses and see how to improve. In software, without clear performance measures, few of us can understand our personal strengths and weaknesses or see how to improve. The methods in this book will help you to assess your own performance, to identify ways to improve, and to guide your improvement efforts.

In addition to helping you improve your personal performance, this book will also help you build the engineering skills needed for large-scale software work. You will learn how to make accurate plans, how to estimate the accuracy of these plans, and how to track your performance against them. You will use defect management, design and code reviews, design templates, and process analysis. You will do this with a defined and measured personal software process. These measurement and analysis disciplines will help you to evaluate your performance, to understand your strengths, and to see where you should try to improve. From all of this you will develop the tools you need to continue personal improvement throughout your professional career.What’s Involved in Learning the PSP

In learning the PSP, the benefits you get will depend on the effort you invest. Although there are many ways to organize a PSP course, the basic requirements are reading the 14 chapters of this book and completing the programming and report exercises provided on the SEI Web site (www.sei.cmu.edu/tsp/psp.html). This web site also includes various course plans. The original PSP course called for a total of ten exercise programs and five report exercises. Other strategies have used various numbers of program exercises, but the basic requirement is to write a program at each of the six PSP process levels plus an additional two to four programs to master the methods and build the data to support your continuing work.

Reading the chapters should not take too long; the time it takes to write the programs can vary widely. These PSP exercise programs have now been written many thousands of times, and I use a sample of 8,100 sets of PSP program data for many examples in this book. In writing these programs, half of the developers spent less than four hours each, and one-third averaged under three hours. To minimize your time, use the programming language and environment that you know best, and keep your designs simple and straightforward.

Because the PSP course involves writing programs, people often think it is a programming course. It is not. Even after writing all of the assigned programs, if you did not follow the prescribed PSP processes and gather, analyze, and use all of the specified data, you would not learn the PSP. This is a process course, and to avoid wasting your time, follow the prescribed process to write each program. If you have problems doing this, ask your instructor for help.

The following two suggestions will ensure that you get the most from the PSP course. First, do not substitute programs from your work for those called for by the text. Of the thousands of developers who have completed PSP training, no one has done this successfully. Taking this course involves learning new and unfamiliar methods. The exercises in this course are like experiments, and working programmers are universally reluctant to experiment with unfamiliar methods when they work on a project. Second, do not merely read the book and then try to apply the methods without doing the exercises. Until you have completed the course and the exercises, you will not be able to apply the methods on the job. At least, nobody has done so thus far. Book Overview

The 14 chapters of this book introduce the PSP methods in steps. Chapter 1 describes the overall principles of the PSP and the introduction strategy. Chapters 2 and 3 explain how to follow a defined process and how to gather and use the data required to manage a programming development job. Chapters 4, 5, 6, and 7 cover estimating and planning, and Chapters 8 through 12 cover quality management and design. Chapter 13 describes how to use the PSP for various kinds of work, and Chapter 14 describes how the PSP methods are used in the TSP process and how the TSP guides PSP-trained software engineers in using these methods on a project. It also discusses the personal issues involved in learning and using the PSP.Support Materials

This book has extensive support materials, which are available at www.sei.cmu.edu/tsp/psp.html. The support items are a data-gathering and planning tool, the PSP exercise assignment kits, and reference materials. Also included are pointers to PSP course descriptions and the addresses of SEI-authorized organizations that can help you to introduce and use the PSP and TSP in your organization. The PSP also be taught as a university course. For this purpose, the online support materials include an instructor’s guide, suggested slides for PSP course lectures, and class exercises. These items are also publicly available on the Web site.Book Background and History

This is the fourth book I have written on the PSP. I wrote A Discipline for Software Engineering in 19953 and I published Introduction to the Personal Software Process in 1997.4 Introduction to the Team Software Process followed in 2000.5 The Discipline book was for a graduate course in computer science, and the introductory books were texts for undergraduate courses. In the intervening years, thousands of software developers have taken the PSP course and hundreds of TSP teams have used the PSP methods on their projects. The results have been far better than I had hoped.

This experience demonstrated that a PSP textbook was needed for industrial software developers. Although Discipline for Software Engineering covers all of the required materials, it also includes a number of topics that are of more academic interest and are not essential for teaching industrial software developers. Because course duration is a principal concern for industrial organizations, these more academic topics have been omitted from this book.Notes

1. The Standish Group International, Inc., 586 Olde King’s Highway, Dennis, MA 02638; www.standishgroup.com.
2. Personal Software Process, PSP, Team Software Process, and TSP are service marks of Carnegie Mellon University.
3. Watts Humphrey, A Discipline for Software Engineering, Addison-Wesley, 1995.
4. Watts Humphrey, Introduction to the Personal Software Process, Addison-Wesley, 1997.
5. Watts Humphrey, Introduction to the Team Software Process, Addison-Wesley, 2000.

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FROM THE PUBLISHER

The record of most software-development groups is embarrassing: More than half of all software projects are significantly late and over budget, and nearly a quarter of them are cancelled without ever being completed. As a result, less than 30 percent of software-development projects are considered successful. While developers recognize that unrealistic schedules, inadequate resources, and unstable requirements are often to blame for such failures, few know how to solve these problems.

By learning the Personal Software Process (PSP) and applying it in the Team Software Process (TSP), individual developers and development teams gain the skills and practices needed to deliver quality software products on predictable schedules. PSPSM: A Self-Improvement Process for Software Engineers is the essential guide to learning how to apply these disciplines in today's software-development environment.

The book scales down industrial software practices to fit the needs of module-sized program development. It then walks readers through a progressive sequence of software processes that provide a sound foundation for large-scale software development. By doing the exercises and using the methods described in this book, developers will learn how to use the methods themselves on module-sized programs and, later, on larger projects.

In addition to helping developers improve their personal performance, this book will help them build the engineering skills needed for large-scale software work. Readers will master how to make accurate plans, estimate the accuracy of these plans, and track their performance against them. They will also learn how to use defect management, design andcode reviews, design templates, and process analysis. These measurement and analysis disciplines will help readers to evaluate their performance, understand their strengths, and see where there is room for improvement.