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Technical Report CMU/SEI-93-TR-024 ESC-TR-93-177 February 1993 Capability Maturity Model SM for Software, Version 1.1 Mark C. Paulk Bill Curtis Mary Beth Chrissis Charles V. Weber

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  • Technical ReportCMU/SEI-93-TR-024ESC-TR-93-177February 1993

    Capability Maturity ModelSM

    for Software, Version 1.1

    Mark C. Paulk

    Bill Curtis

    Mary Beth Chrissis

    Charles V. Weber

  • Software Engineering InstituteCarnegie Mellon University

    Pittsburgh, Pennsylvania 15213

    Unlimited distribution subject to the copyright.

    Technical ReportCMU/SEI-93-TR-024

    ESC-TR-93-177February 1993

    Capability Maturity ModelSM

    for Software, Version 1.1

    Mark C. Paulk

    Bill Curtis

    Mary Beth Chrissis

    Charles V. Weber

  • This report was prepared for the

    SEI Joint Program OfficeHQ ESC/AXS5 Eglin StreetHanscom AFB, MA 01731-2116

    The ideas and findings in this report should not be construed as an official DoD position. It is published in theinterest of scientific and technical information exchange.

    FOR THE COMMANDER

    (signature on file)

    Thomas R. Miller, Lt Col, USAFSEI Joint Program Office

    This work is sponsored by the U.S. Department of Defense.

    Copyright 1996 by Carnegie Mellon University.

    Permission to reproduce this document and to prepare derivative works from this document for internal use isgranted, provided the copyright and No Warranty statements are included with all reproductions and derivativeworks.

    Requests for permission to reproduce this document or to prepare derivative works of this document for externaland commercial use should be addressed to the SEI Licensing Agent.

    NO WARRANTY

    THIS CARNEGIE MELLON UNIVERSITY AND SOFTWARE ENGINEERING INSTITUTE MATERIALIS FURNISHED ON AN AS-IS BASIS. CARNEGIE MELLON UNIVERSITY MAKES NO WARRAN-TIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED, AS TO ANY MATTER INCLUDING, BUT NOTLIMITED TO, WARRANTY OF FITNESS FOR PURPOSE OR MERCHANTIBILITY, EXCLUSIVITY, ORRESULTS OBTAINED FROM USE OF THE MATERIAL. CARNEGIE MELLON UNIVERSITY DOESNOT MAKE ANY WARRANTY OF ANY KIND WITH RESPECT TO FREEDOM FROM PATENT,TRADEMARK, OR COPYRIGHT INFRINGEMENT.

    This work was created in the performance of Federal Government Contract Number F19628-95-C-0003 withCarnegie Mellon University for the operation of the Software Engineering Institute, a federally funded researchand development center. The Government of the United States has a royalty-free government-purpose license touse, duplicate, or disclose the work, in whole or in part and in any manner, and to have or permit others to do so,for government purposes pursuant to the copyright license under the clause at 52.227-7013.

    This document is available through Research Access, Inc., 800 Vinial Street, Pittsburgh, PA 15212.Phone: 1-800-685-6510. FAX: (412) 321-2994. RAI also maintains a World Wide Web home page. The URL ishttp://www.rai.com

    Copies of this document are available through the National Technical Information Service (NTIS). For informa-tion on ordering, please contact NTIS directly: National Technical Information Service, U.S. Department ofCommerce, Springfield, VA 22161. Phone: (703) 487-4600.

    This document is also available through the Defense Technical Information Center (DTIC). DTIC provides ac-cess to and transfer of scientific and technical information for DoD personnel, DoD contractors and potential con-tractors, and other U.S. Government agency personnel and their contractors. To obtain a copy, please contactDTIC directly: Defense Technical Information Center, Attn: FDRA, Cameron Station, Alexandria, VA 22304-6145. Phone: (703) 274-7633.

    Use of any trademarks in this report is not intended in any way to infringe on the rights of the trademark holder.

  • Table of Contents

    Acknowledgments.......................................................................................................vTo the Reader.............................................................................................................viiWhat is the Purpose of This Paper?.....................................................................viiiWho Should Read This Paper?............................................................................viiiHow is This Paper Organized?.................................................................................ixWhat Are the Other CMM Products?.......................................................................xHow Do You Receive More Information?............................................................xi1 The Process Maturity Framework.......................................................................1

    1.1 Immature Versus Mature Software Organizations................................11.2 Fundamental Concepts Underlying Process Maturity...........................31.3 Overview of the Capability Maturity Model............................................4

    2 The Five Levels of Software Process Maturity.................................................72.1 Behavioral Characterization of the Maturity Levels.............................9

    2.1.1 Level 1 - The Initial Level..............................................................102.1.2 Level 2 - The Repeatable Level.....................................................102.1.3 Level 3 - The Defined Level...........................................................112.1.4 Level 4 - The Managed Level........................................................122.1.5 Level 5 - The Optimizing Level....................................................13

    2.2 Understanding the Maturity Levels........................................................142.2.1 Understanding the Initial Level...................................................152.2.2 Understanding the Repeatable and Defined Levels.................152.2.3 Understanding the Managed and Optimizing Levels.............16

    2.3 Visibility Into the Software Process.........................................................192.4 Process Capability and the Prediction of Performance.........................222.5 Skipping Maturity Levels...........................................................................25

    3 Operational Definition of the Capability Maturity Model...........................273.1 Internal Structure of the Maturity Levels..............................................273.2 Maturity Levels............................................................................................303.3 Key Process Areas.........................................................................................303.4 Common Features.......................................................................................373.5 Key Practices..................................................................................................39

    4 Using the CMM.....................................................................................................434.1 Software Process Assessment and Software Capability

    Evaluation Methods....................................................................................444.2 Differences Between Software Process Assessments and

    Software Capability Evaluations...............................................................474.3 Other Uses of the CMM in Process Improvement...............................49

    CMU/SEI-93-TR-24 Capability Maturity Model i

  • Table of Contents

    5 Future Directions of the CMM...........................................................................515.1 What the CMM Does Not Cover..............................................................515.2 Near-Term Activities..................................................................................515.3 Long-Term Activities..................................................................................525.4 Conclusion....................................................................................................53

    6 References...............................................................................................................55Appendix A: Goals for Each Key Process Area....................................................59

    A.1 The Key Process Areas for Level 2: Repeatable.....................................59A.2 The Key Process Areas for Level 3: Defined..........................................61A.3 The Key Process Areas for Level 4: Managed........................................62A.4 The Key Process Areas for Level 5: Optimizing...................................63

    ii Capability Maturity Model CMU/SEI-91-TR-24

  • List of Figures

    Figure 2.1 The Five Levels of Software Process Maturity..................................8Figure 2.2 The Juran Trilogy Diagram: Quality Planning, Quality

    Control, and Quality Improvement..................................................17Figure 2.3 A Management View of Visibility into the Software Process

    at Each Maturity Level..........................................................................20Figure 2.4 Process Capability as Indicated by Maturity Level...........................23Figure 3.1 The CMM Structure..............................................................................29Figure 3.2 The Key Process Areas by Maturity Level.........................................31Figure 3.3 Building the CMM Structure: An Example of a Key Practice......40Figure 4.1 Common Steps in Software Process Assessments and

    Software Capability Evaluations.........................................................45

    CMU/SEI-93-TR-24 Capability Maturity Model iii

  • List of Figures

    iv Capability Maturity Model CMU/SEI-91-TR-24

  • Acknowledgments

    The description of the Capability Maturity Model for Software was initiallyproduced by a dedicated group of people who spent many hours discussingthe model and its features and then trying to document it in CMM v1.0.This group consisted of Mark Paulk, Bill Curtis, Mary Beth Chrissis, EdwardAverill, Judy Bamberger, Tim Kasse, Mike Konrad, Jeff Perdue, CharlieWeber, and Jim Withey.

    This paper is based on the vision of Watts Humphrey, first director of theSEI's Software Process Program. It took several drafts to evolve this paperinto the final product. Jim Withey, Mark Paulk, and Cynthia Wiseproduced an early draft in 1990. Watts Humphrey provided a second draftof the document, and Mark Paulk then took over the paper and remainedbook boss until the end. Mary Beth Chrissis and Bill Curtis helped Markproduce the CMM v1.0 revision of this paper in August, 1991. Mark Paulkproduced the CMM v1.1 revision of the paper, which is this technical report.

    At various stages, several people contributed to the concepts expressed inthis paper. They include Joe Besselman, Marilyn Bush, Anita Carleton,Marty Carlson, Betty Deimel, Suzie Garcia, Richard Kauffold, Steve Masters,Mary Merrill, Jim Over, George Pandelios, Jane Siegel and Charlie Weber.

    We appreciate the administrative help from Todd Bowman, DorothyJosephson, Debbie Punjack, Carolyn Tady, Marcia Theoret, Andy Tsounos,and David White; and the editorial assistance from Mary Beth Chrissis,Suzanne Couturiaux, and Bill Pollak. Renne Dutkowski from theAmerican Institutes for Research provided suggestions for the design of thedocument.

    CMU/SEI-93-TR-24 Capability Maturity Model v

  • Acknowledgments

    vi Capability Maturity Model CMU/SEI-93-TR-24

  • To the Reader

    In November 1986, the Software Engineering Institute (SEI), with assistancefrom the Mitre Corporation, began developing a process maturityframework that would help organizations improve their software process.This effort was initiated in response to a request to provide the federalgovernment with a method for assessing the capability of its softwarecontractors. In September 1987, the SEI released a brief description of theprocess maturity framework [Humphrey 87a] and a maturity questionnaire[Humphrey87b]. The SEI intended the maturity questionnaire to provide asimple tool for identifying areas where an organization's software processneeded improvement. Unfortunately, the maturity questionnaire was toooften regarded as "the model" rather than as a vehicle for exploring processmaturity issues.

    After four years of experience with the software process maturity frameworkand the preliminary version of the maturity questionnaire, the SEI evolvedthe software process maturity framework into the Capability MaturityModel for Software (CMM) [Paulk91, Weber91]. The CMM is based onknowledge acquired from software process assessments and extensivefeedback from both industry and government. By elaborating the maturityframework, a model has emerged that provides organizations with moreeffective guidance for establishing process improvement programs.

    The initial release of the CMM, Version 1.0, was reviewed and used by thesoftware community during 1991 and 1992. A workshop was held in April,1992 on CMM v1.0, which was attended by about 200 software professionals.This version of the CMM, Version 1.1, is the result of the feedback from thatworkshop and ongoing feedback from the software community.

    The CMM is the foundation for systematically building a set of tools,including a maturity questionnaire, which are useful in software processimprovement. The essential point to remember is that the model, not aquestionnaire, is the basis for improving the software process. This paper isintended to introduce the reader to CMM v1.1.

    CMU/SEI-93-TR-24 Capability Maturity Model vii

  • To the Reader

    What is the Purpose of This Paper?

    This paper provides a technical overview of the Capability Maturity Modelfor Software and reflects Version 1.1. Specifically, this paper describes theprocess maturity framework of five maturity levels, the structuralcomponents that comprise the CMM, how the CMM is used in practice, andfuture directions of the CMM. This paper serves as one of the best sourcesfor understanding the CMM, and it should clear up some of themisconceptions associated with software process maturity as advocated bythe SEI.

    The SEI has worked with industry and government to refine and expandthe model, and software organizations are encouraged to focus on the CMMrather than on the maturity questionnaire. The SEI has developed, and isdeveloping, a suite of process products to encourage this focus. This paper[Paulk93a], in combination with the "Key Practices of the Capability MaturityModel, Version 1.1" [Paulk93b], comprises CMM v1.1. The "Key Practices ofthe Capability Maturity Model, Version 1.1" describes the key practices foreach level of the CMM. This paper describes the principles underlyingsoftware process maturity and is intended to help software organizationsuse CMM v1.1 as a guide to improve the maturity of their softwareprocesses.

    Who Should Read This Paper?

    This paper presents an introduction to the CMM and its associated products.Therefore, anyone who is interested in learning about the CMM shouldread this paper. However, this paper assumes that the reader has someknowledge of, and experience in, developing and/or maintaining software,as well as an understanding of the problems that the software communityfaces today.

    viii Capability Maturity Model CMU/SEI-93-TR-24

  • To the Reader

    This document can be used in several ways:

    by anyone wanting to understand the key practices that are part ofeffective processes for developing or maintaining software,

    by anyone wanting to identify the key practices that are needed toachieve the next maturity level in the CMM,

    by organizations wanting to understand and improve their capabilityto develop software effectively,

    by acquisition organizations or prime contractors wanting to knowthe risks of having a particular software organization perform thework of a contract,

    by the SEI as the basis for developing questions for the maturityquestionnaire, and

    by instructors preparing teams to perform software processassessments or software capability evaluations.

    How is This Paper Organized?

    This paper has five chapters:

    Chapter 1 Defines the concepts necessary to understandthe CMM and the motivation and purposebehind it.

    CMU/SEI-93-TR-24 Capability Maturity Model ix

  • To the Reader

    Chapter 2 Describes the five levels of the CMM and theprinciples that underlie them.

    Chapter 3 Describes how the CMM is structured intokey process areas, organized by commonfeatures, and described in terms of keypractices.

    Chapter 4 Provides a high-level overview of how theCMM provides guidance for software processassessments, software capability evaluations,and process improvement programs.

    Chapter 5 Concludes by providing a description offuture directions for the CMM and its relatedproducts.

    What Are the Other CMM Products?

    Although this paper can be read in isolation, it is designed to be thelaunching point for other products. This paper and the associated productshelp the reader understand and use the CMM. All of the CMM-basedproducts have been, or will be, systematically derived from the model. Atthe time of this writing, most of these products are not available in theirfinal form, although preliminary versions are in various stages of pilottesting and release.

    x Capability Maturity Model CMU/SEI-93-TR-24

  • To the Reader

    The CMM-based set of products includes several diagnostic tools, which areused by software process assessment1 and software capability evaluation2

    teams to identify strengths, weaknesses, and risks of an organization'ssoftware process. Probably the best known of these is the maturityquestionnaire. The software process assessment and software capabilityevaluation methods and training also rely on the CMM.

    The users of these products form a community dedicated to improving thematurity of their software process. The SEI will continue to work with thesoftware community to enhance the model and its associated products.

    How Do You Receive More Information?

    For further information regarding the CMM and its associated products,including training on the CMM and how to perform software processassessments and software capability evaluations, contact:

    SEI Customer RelationsSoftware Engineering InstituteCarnegie Mellon UniversityPittsburgh, PA 15213-3890(412) 268-5800Internet: [email protected]

    1 A software process assessment is an appraisal by a trained team of software professionals todetermine the state of an organization's current software process, to determine the high-prioritysoftware process-related issues facing an organization, and to obtain the organizational support forsoftware process improvement.2 A software capability evaluation is an appraisal by a trained team of professionals to identifycontractors who are qualified to perform the software work or to monitor the state of the softwareprocess used on an existing software effort.

    CMU/SEI-93-TR-24 Capability Maturity Model xi

  • To the Reader

    SEI technical reports, such as this paper and the "Key Practices of theCapability Maturity Model, Version 1.1," are directly available from theDefense Technical Information Center (DTIC), the National TechnicalInformation Service (NTIS), and Research Access Inc. (RAI). Thesedocuments can be obtained by contacting:

    RAI: Research Access Inc.3400 Forbes AvenueSuite 302Pittsburgh, PA 15213Telephone: (800) 685-6510FAX: (412) 682-6530

    NTIS: National Technical Information ServiceU.S. Department of CommerceSpringfield, VA 22161-2103Telephone: (703) 487-4600

    DTIC: Defense Technical Information CenterATTN: FDRA Cameron StationAlexandria, VA 22304-6145Telephone: (703) 274-7633

    xii Capability Maturity Model CMU/SEI-93-TR-24

  • To the Reader

    SEI technical reports are also available via Internet. To use anonymous ftpfrom a Unix system on Internet:

    ftp ftp.sei.cmu.edu3

    login: anonymouspassword: cd pub/cmmget READ.MEget quit

    The file READ.ME contains information on what files are available. OtherSEI publications are available in a similar manner.

    3 The SEI ftp machine address is 128.237.2.179.

    CMU/SEI-93-TR-24 Capability Maturity Model xiii

  • To the Reader

    xiv Capability Maturity Model CMU/SEI-93-TR-24

  • 1 The Process MaturityFramework

    After two decades of unfulfilled promises about productivity and qualitygains from applying new software methodologies and technologies,industry and government organizations are realizing that theirfundamental problem is the inability to manage the software process[DoD87]. The benefits of better methods and tools cannot be realized in themaelstrom of an undisciplined, chaotic project. In many organizations,projects are often excessively late and double the planned budget [Siegel90].In such instances, the organization frequently is not providing theinfrastructure and support necessary to help projects avoid these problems.

    Even in undisciplined organizations, however, some individual softwareprojects produce excellent results. When such projects succeed, it isgenerally through the heroic efforts of a dedicated team, rather thanthrough repeating the proven methods of an organization with a maturesoftware process. In the absence of an organization-wide software process,repeating results depends entirely on having the same individuals availablefor the next project. Success that rests solely on the availability of specificindividuals provides no basis for long-term productivity and qualityimprovement throughout an organization. Continuous improvement canoccur only through focused and sustained effort towards building a processinfrastructure of effective software engineering and management practices.

    1.1 Immature Versus Mature SoftwareOrganizations

    Setting sensible goals for process improvement requires an understandingof the difference between immature and mature software organizations. Inan immature software organization, software processes are generallyimprovised by practitioners and their management during the course of theproject. Even if a software process has been specified, it is not rigorously

    CMU/SEI-93-TR-24 Capability Maturity Model 1

  • The Process Maturity Framework

    followed or enforced. The immature software organization is reactionary,and managers are usually focused on solving immediate crises (betterknown as fire fighting). Schedules and budgets are routinely exceededbecause they are not based on realistic estimates. When hard deadlines areimposed, product functionality and quality are often compromised to meetthe schedule.

    In an immature organization, there is no objective basis for judging productquality or for solving product or process problems. Therefore, productquality is difficult to predict. Activities intended to enhance quality such asreviews and testing are often curtailed or eliminated when projects fallbehind schedule.

    On the other hand, a mature software organization possesses anorganization-wide ability for managing software development andmaintenance processes. The software process is accurately communicated toboth existing staff and new employees, and work activities are carried outaccording to the planned process. The processes mandated are fit for use[Humphrey91b] and consistent with the way the work actually gets done.These defined processes are updated when necessary, and improvementsare developed through controlled pilot-tests and/or cost benefit analyses.Roles and responsibilities within the defined process are clear throughoutthe project and across the organization.

    In a mature organization, managers monitor the quality of the softwareproducts and customer satisfaction. There is an objective, quantitative basisfor judging product quality and analyzing problems with the product andprocess. Schedules and budgets are based on historical performance and arerealistic; the expected results for cost, schedule, functionality, and quality ofthe product are usually achieved. In general, a disciplined process isconsistently followed because all of the participants understand the value ofdoing so, and the necessary infrastructure exists to support the process.

    2 Capability Maturity Model CMU/SEI-93-TR-24

  • The Process Maturity Framework

    Capitalizing on these observations about immature and mature softwareorganizations requires construction of a software process maturityframework. This framework describes an evolutionary path from ad hoc,chaotic processes to mature, disciplined software processes. Without thisframework, improvement programs may prove ineffective because thenecessary foundation for supporting successive improvements has not beenestablished. The software process maturity framework emerges fromintegrating the concepts of software process, software process capability,software process performance, and software process maturity, all of whichare defined in succeeding paragraphs.

    1.2 Fundamental Concepts Underlying ProcessMaturity

    According to Webster's dictionary, a process is "a system of operations inproducing something ... a series of actions, changes, or functions thatachieve an end or result." The IEEE defines a process as "a sequence of stepsperformed for a given purpose" [IEEE-STD-610]. A software process can bedefined as a set of activities, methods, practices, and transformations thatpeople use to develop and maintain software and the associated products(e.g., project plans, design documents, code, test cases, and user manuals).As an organization matures, the software process becomes better definedand more consistently implemented throughout the organization.

    Software process capability describes the range of expected results that can beachieved by following a software process. The software process capability ofan organization provides one means of predicting the most likely outcomesto be expected from the next software project the organization undertakes.

    Software process performance represents the actual results achieved byfollowing a software process. Thus, software process performance focuseson the results achieved, while software process capability focuses on resultsexpected. Based on the attributes of a specific project and the context within

    CMU/SEI-93-TR-24 Capability Maturity Model 3

  • The Process Maturity Framework

    which it is conducted, the actual performance of the project may not reflectthe full process capability of the organization; i.e., the capability of theproject is constrained by its environment. For instance, radical changes inthe application or technology undertaken may place a project' s staff on alearning curve that causes their project's capability, and performance, to fallshort of the organization's full process capability.

    Software process maturity is the extent to which a specific process isexplicitly defined, managed, measured, controlled, and effective. Maturityimplies a potential for growth in capability and indicates both the richnessof an organization's software process and the consistency with which it isapplied in projects throughout the organization. The software process iswell-understood throughout a mature organization, usually throughdocumentation and training, and the process is continually beingmonitored and improved by its users. The capability of a mature softwareprocess is known. Software process maturity implies that the productivityand quality resulting from an organizations software process can beimproved over time through consistent gains in the discipline achieved byusing its software process.

    As a software organization gains in software process maturity, itinstitutionalizes its software process via policies, standards, andorganizational structures. Institutionalization entails building aninfrastructure and a corporate culture that supports the methods, practices,and procedures of the business so that they endure after those whooriginally defined them have gone.

    1.3 Overview of the Capability Maturity Model

    Although software engineers and managers often know their problems ingreat detail, they may disagree on which improvements are most important.Without an organized strategy for improvement, it is difficult to achieveconsensus between management and the professional staff on what

    4 Capability Maturity Model CMU/SEI-93-TR-24

  • The Process Maturity Framework

    improvement activities to undertake first. To achieve lasting results fromprocess improvement efforts, it is necessary to design an evolutionary paththat increases an organization's software process maturity in stages. Thesoftware process maturity framework [Humphrey 87a] orders these stages sothat improvements at each stage provide the foundation on which to buildimprovements undertaken at the next stage. Thus, an improvementstrategy drawn from a software process maturity framework provides aroadmap for continuous process improvement. It guides advancement andidentifies deficiencies in the organization; it is not intended to provide aquick fix for projects in trouble.

    The Capability Maturity Model for Software provides software organizationswith guidance on how to gain control of their processes for developing andmaintaining software and how to evolve toward a culture of softwareengineering and management excellence. The CMM was designed to guidesoftware organizations in selecting process improvement strategies bydetermining current process maturity and identifying the few issues mostcritical to software quality and process improvement. By focusing on alimited set of activities and working aggressively to achieve them, anorganization can steadily improve its organization-wide software process toenable continuous and lasting gains in software process capability.

    The staged structure of the CMM is based on principles of product qualitythat have existed for the last sixty years. In the 1930s, Walter Shewart,promulgated the principles of statistical quality control. His principles werefurther developed and successfully demonstrated in the work of W.Edwards Deming [Deming86] and Joseph Juran [Juran88, Juran89]. Theseprinciples have been adapted by the SEI into a maturity framework thatestablishes a project management and engineering foundation forquantitative control of the software process, which is the basis forcontinuous process improvement.

    The maturity framework into which these quality principles have beenadapted was first inspired by Philip Crosby of in his book Quality is Free[Crosby79]. Crosby's quality management maturity grid describes five

    CMU/SEI-93-TR-24 Capability Maturity Model 5

  • The Process Maturity Framework

    evolutionary stages in adopting quality practices. This maturity frameworkwas adapted to the software process by Ron Radice and his colleagues,working under the direction of Watts Humphrey at IBM [Radice85].Humphrey brought this maturity framework to the Software EngineeringInstitute in 1986, added the concept of maturity levels, and developed thefoundation for its current use throughout the software industry.

    Early versions of Humphrey's maturity framework are described in SEItechnical reports [Humphrey87a, Humphrey87b], papers [Humphrey88], andin his book, Managing the Software Process [Humphrey89]. A preliminarymaturity questionnaire [Humphrey87b] was released in 1987 as a tool toprovide organizations with a way to characterize the maturity of theirsoftware processes. Two methods, software process assessment and softwarecapability evaluation, were developed to appraise software process maturityin 1987. Since 1990, the SEI, with the help of many people fromgovernment and industry, has further expanded and refined the modelbased on several years of experience in its application to software processimprovement.

    6 Capability Maturity Model CMU/SEI-93-TR-24

  • 2 The Five Levels of SoftwareProcess Maturity

    Continuous process improvement is based on many small, evolutionarysteps rather than revolutionary innovations [Imai86]. The CMM provides aframework for organizing these evolutionary steps into five maturity levelsthat lay successive foundations for continuous process improvement.These five maturity levels define an ordinal scale for measuring thematurity of an organization's software process and for evaluating itssoftware process capability. The levels also help an organization prioritizeits improvement efforts.

    A maturity level is a well-defined evolutionary plateau toward achieving amature software process. Each maturity level provides a layer in thefoundation for continuous process improvement. Each level comprises aset of process goals that, when satisfied, stabilize an important component ofthe software process. Achieving each level of the maturity frameworkestablishes a different component in the software process, resulting in anincrease in the process capability of the organization.

    Organizing the CMM into the five levels shown in Figure 2.1 prioritizesimprovement actions for increasing software process maturity. The labeledarrows in Figure 2.1 indicate the type of process capability beinginstitutionalized by the organization at each step of the maturityframework.

    CMU/SEI-93-TR-24 Capability Maturity Model 7

  • The Five Levels of Software Process Maturity

    Initial(1)

    Repeatable(2)

    Defined(3)

    Managed(4)

    Optimizing(5)

    Disciplinedprocess

    Standard,consistentprocess

    Predictableprocess

    Continuouslyimprovingprocess

    Figure 2.1 The Five Levels of Software Process Maturity

    The following characterizations of the five maturity levels highlight theprimary process changes made at each level:

    1) Initial The software process is characterized as ad hoc, andoccasionally even chaotic. Few processes are defined, andsuccess depends on individual effort.

    8 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    2) Repeatable Basic project management processes are established totrack cost, schedule, and functionality. The necessaryprocess discipline is in place to repeat earlier successes onprojects with similar applications.

    3) Defined The software process for both management andengineering activities is documented, standardized, andintegrated into a standard software process for theorganization. All projects use an approved, tailoredversion of the organization's standard software process fordeveloping and maintaining software.

    4) Managed Detailed measures of the software process and productquality are collected. Both the software process andproducts are quantitatively understood and controlled.

    5) Optimizing Continuous process improvement is enabled byquantitative feedback from the process and from pilotinginnovative ideas and technologies.

    2.1 Behavioral Characterization of the MaturityLevels

    Maturity Levels 2 through 5 can be characterized through the activitiesperformed by the organization to establish or improve the software process,by activities performed on each project, and by the resulting processcapability across projects. A behavioral characterization of Level 1 isincluded to establish a base of comparison for process improvements athigher maturity levels.

    CMU/SEI-93-TR-24 Capability Maturity Model 9

  • The Five Levels of Software Process Maturity

    2.1.1 Level 1 - The Initial Level

    At the Initial Level, the organization typically does not provide a stableenvironment for developing and maintaining software. When anorganization lacks sound management practices, the benefits of goodsoftware engineering practices are undermined by ineffective planning andreaction-driven commitment systems.

    During a crisis, projects typically abandon planned procedures and revert tocoding and testing. Success depends entirely on having an exceptionalmanager and a seasoned and effective software team. Occasionally, capableand forceful software managers can withstand the pressures to takeshortcuts in the software process; but when they leave the project, theirstabilizing influence leaves with them. Even a strong engineering processcannot overcome the instability created by the absence of soundmanagement practices.

    The software process capability of Level 1 organizations is unpredictablebecause the software process is constantly changed or modified as the workprogresses (i.e., the process is ad hoc). Schedules, budgets, functionality, andproduct quality are generally unpredictable. Performance depends on thecapabilities of individuals and varies with their innate skills, knowledge,and motivations. There are few stable software processes in evidence, andperformance can be predicted only by individual rather than organizationalcapability.

    2.1.2 Level 2 - The Repeatable Level

    At the Repeatable Level, policies for managing a software project andprocedures to implement those policies are established. Planning andmanaging new projects is based on experience with similar projects. Anobjective in achieving Level 2 is to institutionalize effective management

    10 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    processes for software projects, which allow organizations to repeatsuccessful practices developed on earlier projects, although the specificprocesses implemented by the projects may differ. An effective process canbe characterized as practiced, documented, enforced, trained, measured, andable to improve.

    Projects in Level 2 organizations have installed basic software managementcontrols. Realistic project commitments are based on the results observedon previous projects and on the requirements of the current project. Thesoftware managers for a project track software costs, schedules, andfunctionality; problems in meeting commitments are identified when theyarise. Software requirements and the work products developed to satisfythem are baselined, and their integrity is controlled. Software projectstandards are defined, and the organization ensures they are faithfullyfollowed. The software project works with its subcontractors, if any, toestablish a strong customer-supplier relationship.

    The software process capability of Level 2 organizations can be summarizedas disciplined because planning and tracking of the software project is stableand earlier successes can be repeated. The project's process is under theeffective control of a project management system, following realistic plansbased on the performance of previous projects.

    2.1.3 Level 3 - The Defined Level

    At the Defined Level, the standard process for developing and maintainingsoftware across the organization is documented, including both softwareengineering and management processes, and these processes are integratedinto a coherent whole. This standard process is referred to throughout theCMM as the organization's standard software process. Processes establishedat Level 3 are used (and changed, as appropriate) to help the softwaremanagers and technical staff perform more effectively. The organizationexploits effective software engineering practices when standardizing itssoftware processes. There is a group that is responsible for the

    CMU/SEI-93-TR-24 Capability Maturity Model 11

  • The Five Levels of Software Process Maturity

    organization's software process activities, e.g., a software engineeringprocess group, or SEPG [Fowler90]. An organization-wide training programis implemented to ensure that the staff and managers have the knowledgeand skills required to fulfill their assigned roles.

    Projects tailor the organization's standard software process to develop theirown defined software process, which accounts for the unique characteristicsof the project. This tailored process is referred to in the CMM as theproject's defined software process. A defined software process contains acoherent, integrated set of well-defined software engineering andmanagement processes. A well-defined process can be characterized asincluding readiness criteria, inputs, standards and procedures forperforming the work, verification mechanisms (such as peer reviews),outputs, and completion criteria. Because the software process is welldefined, management has good insight into technical progress on allprojects.

    The software process capability of Level 3 organizations can be summarizedas standard and consistent because both software engineering andmanagement activities are stable and repeatable. Within establishedproduct lines, cost, schedule, and functionality are under control, andsoftware quality is tracked. This process capability is based on a common,organization-wide understanding of the activities, roles, and responsibilitiesin a defined software process.

    2.1.4 Level 4 - The Managed Level

    At the Managed Level, the organization sets quantitative quality goals forboth software products and processes. Productivity and quality aremeasured for important software process activities across all projects as partof an organizational measurement program. An organization-widesoftware process database is used to collect and analyze the data availablefrom the projects' defined software processes. Software processes areinstrumented with well-defined and consistent measurements at Level 4.

    12 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    These measurements establish the quantitative foundation for evaluatingthe projects' software processes and products.

    Projects achieve control over their products and processes by narrowing thevariation in their process performance to fall within acceptable quantitativeboundaries. Meaningful variations in process performance can bedistinguished from random variation (noise), particularly withinestablished product lines. The risks involved in moving up the learningcurve of a new application domain are known and carefully managed.

    The software process capability of Level 4 organizations can be summarizedas predictable because the process is measured and operates withinmeasurable limits. This level of process capability allows an organization topredict trends in process and product quality within the quantitative boundsof these limits. When these limits are exceeded, action is taken to correctthe situation. Software products are of predictably high quality.

    2.1.5 Level 5 - The Optimizing Level

    At the Optimizing Level, the entire organization is focused on continuousprocess improvement. The organization has the means to identifyweaknesses and strengthen the process proactively, with the goal ofpreventing the occurrence of defects. Data on the effectiveness of thesoftware process is used to perform cost benefit analyses of new technologiesand proposed changes to the organization's software process. Innovationsthat exploit the best software engineering practices are identified andtransferred throughout the organization.

    Software project teams in Level 5 organizations analyze defects to determinetheir causes. Software processes are evaluated to prevent known types ofdefects from recurring, and lessons learned are disseminated to otherprojects.

    CMU/SEI-93-TR-24 Capability Maturity Model 13

  • The Five Levels of Software Process Maturity

    The software process capability of Level 5 organizations can be characterizedas continuously improving because Level 5 organizations are continuouslystriving to improve the range of their process capability, thereby improvingthe process performance of their projects. Improvement occurs both byincremental advancements in the existing process and by innovations usingnew technologies and methods.

    2.2 Understanding the Maturity Levels

    The CMM is a descriptive model in the sense that it describes essential (orkey) attributes that would be expected to characterize an organization at aparticular maturity level. It is a normative model in the sense that thedetailed practices characterize the normal types of behavior that would beexpected in an organization doing large-scale projects in a governmentcontracting context. The intent is that the CMM is at a sufficient level ofabstraction that it does not unduly constrain how the software process isimplemented by an organization; it simply describes what the essentialattributes of a software process would normally be expected to be.

    In any context in which the CMM is applied, a reasonable interpretation ofthe practices should be used. The CMM must be appropriately interpreted,using informed professional judgment, when the business environment ofthe organization differs significantly from that of a large contractingorganization.

    The CMM is not prescriptive; it does not tell an organization how toimprove. The CMM describes an organization at each maturity levelwithout prescribing the specific means for getting there. It can take severalyears to move from Level 1 to Level 2, and moving between the other levelswill usually take on the order of two years.

    14 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    Software process improvement occurs within the context of theorganization's strategic plans and business objectives, its organizationalstructure, the technologies in use, its social culture, and its managementsystem. The CMM focuses on the process aspects of a Total QualityManagement effort; successful process improvement implies that aspectsoutside the scope of software process are also addressed (e.g., the peopleissues involved with changing the organizational culture that enable theprocess improvements to be implemented and institutionalized).

    2.2.1 Understanding the Initial Level

    Although Level 1 organizations are frequently characterized as having adhoc, even chaotic, processes, they frequently develop products that work,even though they may be over the budget and schedule. Success in Level 1organizations depends on the competence and heroics of the people in theorganization. Selecting, hiring, developing, and/or retaining competentpeople are significant issues for organizations at all levels of maturity, butthey are largely outside the scope of the CMM.

    2.2.2 Understanding the Repeatable and Defined Levels

    As projects grow in size and complexity, attention shifts from technicalissues to organizational and managerial issues the focus of processmaturity [Siegel90, DoD87, GAO-92-48]. Process enables people to workmore effectively by incorporating the lessons learned by the best staff intodocumented processes, building the skills needed to perform those processeseffectively (usually via training), and continually improving by learningfrom the people performing the job.

    To achieve Level 2, management must focus on its own processes toachieve a disciplined software process. Level 2 provides the foundation forLevel 3 because the focus is on management acting to improve its processes

    CMU/SEI-93-TR-24 Capability Maturity Model 15

  • The Five Levels of Software Process Maturity

    before tackling technical and organizational issues at Level 3. Managementestablishes a leadership position in achieving Level 2 by documenting andfollowing project management processes.

    Processes may differ between projects in a Level 2 organization; theorganizational requirement for achieving Level 2 is that there are policiesthat guide the projects in establishing the appropriate managementprocesses. Documented procedures provide the foundation for consistentprocesses that can be institutionalized across the organization, with the aidof training and software quality assurance.

    Level 3 builds on this project management foundation by defining,integrating, and documenting the entire software process. Integration inthis case means that the outputs of one task flow smoothly into the inputsof the next task. When there are mismatches between tasks, they areidentified and addressed in the planning stages of the software process,rather than when they are encountered while enacting the process. One ofthe challenges of Level 3 is to build processes that empower the individualsdoing the work without being overly rigid [Humphrey 91b].

    2.2.3 Understanding the Managed and Optimizing Levels

    Maturity Levels 4 and 5 are relatively unknown territory for the softwareindustry. There are only a few examples of Level 4 and 5 software projectsand organizations [Humphrey91a, Kitson92]. There are too few to drawgeneral conclusions about the characteristics of Level 4 and 5 organizations.The characteristics of these levels have been defined by analogy with otherindustries and the few examples in the software industry exhibiting thislevel of process capability.

    Many characteristics of Levels 4 and 5 are based on the concepts of statisticalprocess control as exemplified in Figure 2.2. The Juran Trilogy Diagram[Juran88] illustrates the primary objectives of process management.

    16 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    Quality Planning Quality Control (during operations)

    Sporadic spike

    Original zone of quality control

    New zone of quality control

    Chronic waste

    Lessons learned

    Time

    Co

    st o

    f p

    oo

    r q

    ual

    ity

    J.M. Juran Wilton, CT Used with the express permission of the Juran Institute, Aug, 1990.

    Quality Improvement

    Figure 2.2 The Juran Trilogy Diagram: Quality Planning, Quality Control,and Quality Improvement

    Juran breaks quality management into three basic managerial processes[Juran88]. The purpose of quality planning is to provide the operatingforces, i.e., the software producers, with the means of producing productsthat can meet customer needs. The operating forces produce the product,but some rework must be done because of quality deficiencies. This waste ischronic because the process was planned that way; quality control is carriedout to prevent things from getting worse. Sporadic spikes in the process, asshown in Figure 2.2, represent fire fighting activities. Chronic wasteprovides an opportunity for improvement; seizing that opportunity isreferred to as quality improvement.

    CMU/SEI-93-TR-24 Capability Maturity Model 17

  • The Five Levels of Software Process Maturity

    The first responsibility, and the focus of Level 4, is process control. Thesoftware process is managed so that it operates stably within a zone ofquality control. There is inevitably some chronic waste, and there may bespikes in the measured results that need to be controlled, but the system isgenerally stable overall. This is where the concept of controlling specialcauses of variation comes into play. Because the process is both stable andmeasured, when some exceptional circumstance occurs, the "special cause"of the variation can be identified and addressed.

    The second responsibility, and the focus of Level 5, is continuous processimprovement. The software process is changed to improve quality, and thezone of quality control moves. A new baseline for performance isestablished that reduces chronic waste. The lessons learned in improvingsuch a process are applied in planning future processes. This is where theconcept of addressing common causes of variation comes to the fore. Thereis chronic waste, in the form of rework, in any system simply due torandom variation. Waste is unacceptable; organized efforts to removewaste result in changing the system, i.e., improving the process by changing"common causes" of inefficiency to prevent the waste from occurring.

    It is anticipated that organizations reaching the highest maturity levels ofthe CMM would have a process that is capable of producing extremelyreliable software within predictable cost and schedule limits. Asunderstanding of the higher maturity levels grows, the existing key processareas will be refined, and others may be added to the model. The CMM isderived from ideas about process that were inspired in manufacturing, butsoftware processes are not dominated by replication issues like amanufacturing process is. The software process is dominated by designissues and is a knowledge-intensive activity [Curtis88].

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  • The Five Levels of Software Process Maturity

    2.3 Visibility Into the Software Process

    Software engineers have detailed insight into the state of a project becausethey have first-hand information on project status and performance.However, on large projects their insight usually is drawn only from theirpersonal experience in their area of responsibility. Those outside the projectwithout first-hand exposure, such as senior managers, lack visibility intothe project's processes and rely on periodic reviews for the information theyrequire to monitor progress. Figure 2.3 illustrates the level of visibility intoproject status and performance afforded to management at each level ofprocess maturity. Each succeeding maturity level incrementally providesbetter visibility into the software process.

    CMU/SEI-93-TR-24 Capability Maturity Model 19

  • The Five Levels of Software Process Maturity

    In Out22

    In Out33

    In Out44

    In Out55

    11 OutIn

    Figure 2.3 A Management View of Visibility Into the Software Process atEach Maturity Level

    At Level 1, the software process is an amorphous entity a black box andvisibility into the project's processes is limited. Since the staging ofactivities is poorly defined, managers have an extremely difficult timeestablishing the status of the project's progress and activities.4

    4 This leads to the Ninety-Ninety Rule: 90% of the project is complete 90% of the time.

    20 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

    Requirements flow into the software process in an uncontrolled manner,and a product results. Software development is frequently viewed as blackmagic, especially by managers who are unfamiliar with software.

    At Level 2, the customer requirements and work products are controlled,and basic project management practices have been established. Thesemanagement controls allow visibility into the project on defined occasions.The process of building the software can be viewed as a succession of blackboxes that allows management visibility at transition points as activity flowsbetween boxes (project milestones). Even though management may notknow the details of what is happening in the box, the products of the processand checkpoints for confirming that the process is working are identifiedand known. Management reacts to problems as they occur.

    At Level 3, the internal structure of the boxes, i.e., the tasks in the project'sdefined software process, is visible. The internal structure represents theway the organization's standard software process has been applied to specificprojects. Both managers and engineers understand their roles andresponsibilities within the process and how their activities interact at theappropriate level of detail. Management proactively prepares for risks thatmay arise. Individuals external to the project can obtain accurate and rapidstatus updates because defined processes afford great visibility into projectactivities.

    At Level 4, the defined software processes are instrumented and controlledquantitatively. Managers are able to measure progress and problems. Theyhave an objective, quantitative basis for making decisions. Their ability topredict outcomes grows steadily more precise as the variability in theprocess grows smaller.

    At Level 5, new and improved ways of building the software are continuallytried, in a controlled manner, to improve productivity and quality.Disciplined change is a way of life as inefficient or defect-prone activities areidentified and replaced or revised. Insight extends beyond existing processes

    CMU/SEI-93-TR-24 Capability Maturity Model 21

  • The Five Levels of Software Process Maturity

    and into the effects of potential changes to processes. Managers are able toestimate and then track quantitatively the impact and effectiveness ofchange.

    2.4 Process Capability and the Prediction of Performance

    The maturity of an organization's software process helps to predict aproject's ability to meet its goals. Projects in Level 1 organizationsexperience wide variations in achieving cost, schedule, functionality, andquality targets. As illustrated in Figure 2.4, three improvements in meetingtargeted goals are observed as the organization's software process matures.

    First, as maturity increases, the difference between targeted results andactual results decreases across projects. For instance, if ten projects of thesame size were targeted to be delivered on May 1, then the average date oftheir delivery would move closer to May 1 as the organization matures.Level 1 organizations often miss their originally scheduled delivery dates bya wide margin, whereas Level 5 organizations should be able to meettargeted dates with considerable accuracy. This is because Level 5organizations use a carefully constructed software process operating withinknown parameters, and the selection of the target date is based on theextensive data they possess about their process and on their performance inapplying it. (This is illustrated in Figure 2.4 by how much of the area underthe curve lies to the right of the target line.)

    22 Capability Maturity Model CMU/SEI-93-TR-24

  • The Five Levels of Software Process Maturity

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    Schedule and cost targetsare typically overrun byLevel 1 organizations.

    Plans based on pastperformance are morerealistic in Level 2 organizations

    With well-defined processes,performance improves inLevel 3 organizations

    Based on quantitativeunderstanding of processand product, performancecontinues to improve inLevel 4 organizations

    Performance continuouslyimproves in Level 5 organizations

    Figure 2.4 Process Capability as Indicated by Maturity Level

    CMU/SEI-93-TR-24 Capability Maturity Model 23

  • The Five Levels of Software Process Maturity

    Second, as maturity increases, the variability of actual results aroundtargeted results decreases. For instance, in Level 1 organizations deliverydates for projects of similar size are unpredictable and vary widely. Similarprojects in a Level 5 organization, however, will be delivered within amuch smaller range. This narrowed variation occurs at the highestmaturity levels because virtually all projects are performing withincontrolled parameters approaching the organization's process capability forcost, schedule, functionality, and quality. (This is illustrated in Figure 2.4 byhow much of the area under the curve is concentrated near the target line.)

    Third, targeted results improve as the maturity of the organizationincreases. That is, as a software organization matures, costs decrease,development time becomes shorter, and productivity and quality increase.In a Level 1 organization, development time can be quite long because ofthe amount of rework that must be performed to correct mistakes. Incontrast, Level 5 organizations use continuous process improvement anddefect prevention techniques to increase process efficiency and eliminatecostly rework, allowing development time to be shortened. (This isillustrated in Figure 2.4 by the horizontal displacement of the target linefrom the origin.)

    The improvements in predicting a project's results represented in Figure 2.4assume that the software project's outcomes become more predictable asnoise, often in the form of rework, is removed from the software process.Unprecedented systems complicate the picture since new technologies andapplications lower the process capability by increasing variability. Even inthe case of unprecedented systems, the management and engineeringpractices characteristic of more mature organizations help identify andaddress problems earlier in the development cycle than they would havebeen detected in less mature organizations. Earlier detection of defectscontributes to project stability and performance by eliminating the reworkduring later phases. Risk management is an integral part of projectmanagement in a mature process. In some cases a mature process meansthat "failed" projects are identified early in the software life cycle andinvestment in a lost cause is minimized.

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  • The Five Levels of Software Process Maturity

    2.5 Skipping Maturity Levels

    The maturity levels in the CMM describe the characteristics of anorganization at a maturity level. Each level builds a foundation forsucceeding levels to leverage for implementing processes effectively andefficiently. Organizations can, however, profitably use processes described ata higher maturity level than they are. Engineering processes, such asrequirements analysis, design, code, and test, are not discussed in the CMMuntil Level 3, yet even Level 1 organizations must perform these activities.A Level 1 or Level 2 organization may be able to perform peer reviews(Level 3), do Pareto analysis (Level 4), or pilot new technologies (Level 5)profitably. When prescribing what steps an organization should take tomove from Level 1 to Level 2, frequently one of the recommendations is toestablish a software engineering process group, which is an attribute ofLevel 3 organizations. Although measurement is the focus of Level 4, it isalso an integral part of the lower maturity levels.

    These processes cannot reach their full potential, however, until the properfoundation is laid. Peer reviews cannot be fully effective, for example,unless they are consistently implemented, even when fires threaten theproject. The maturity levels describe the problems that predominate at alevel. The dominant problems of a Level 1 organization are managerial;other problems tend to be masked by the difficulties in planning andmanaging software projects.

    Skipping levels is counterproductive because each level forms a necessaryfoundation from which to achieve the next level. The CMM identifies thelevels through which an organization must evolve to establish a culture ofsoftware engineering excellence. Processes without the proper foundationfail at the very point they are needed most under stress and they provideno basis for future improvement.

    CMU/SEI-93-TR-24 Capability Maturity Model 25

  • The Five Levels of Software Process Maturity

    A Level 1 organization that is trying to implement a defined process (Level3) before it has established a repeatable process (Level 2) is usuallyunsuccessful because project managers are overwhelmed by schedule andcost pressures. This is the fundamental reason for focusing on managementprocesses before engineering processes. It may seem easier to define andimplement an engineering process than a management process (especiallyin the eyes of technical people), but without management discipline, theengineering process is sacrificed to schedule and cost pressures[Humphrey88].

    An organization that is trying to implement a managed process (Level 4)without the foundation of a defined process is usually unsuccessful becausethere is no common basis for interpreting measurements without definedprocesses. While data can be collected for individual projects, few of themeasurements have significant meaning across projects, and they do notsignificantly increase organizational understanding of the software process.It is difficult to identify meaningful measurements in the absence of definedprocesses because of the variation in the processes being measured.

    An organization that is trying to implement an optimizing process (Level 5)without the foundation of a managed process (Level 4) is likely to failbecause of a lack of understanding of the impact of process changes.Without controlling the process within statistically narrow boundaries(small variations in process measures), there is too much noise in the datato determine objectively whether a specific process improvement has aneffect. Decisions can degenerate into religious wars because littlequantitative foundation exists for making rational, informed decisions.

    The process improvement effort should focus on the needs of theorganization in the context of its business environment. The ability toimplement processes from higher maturity levels does not imply thatmaturity levels can be skipped.

    26 Capability Maturity Model CMU/SEI-93-TR-24

  • 3 Operational Definition of theCapability Maturity Model

    The CMM is a framework representing a path of improvementsrecommended for software organizations that want to increase theirsoftware process capability. This operational elaboration of the CMM isdesigned to support the many ways it will be used. There are at least fouruses of the CMM that are supported:

    Assessments teams will use the CMM to identify strengths andweaknesses in the organization.

    Evaluation teams will use the CMM to identify the risks of selectingamong different contractors for awarding business and to monitorcontracts.

    Managers and technical staff will use the CMM to understand theactivities necessary to plan and implement a software processimprovement program for their organization.

    Process improvement groups, such as an SEPG, will use the CMM asa guide to help them define and improve the software process intheir organization.

    Because of the diverse uses of the CMM, it must be decomposed in sufficientdetail that actual process recommendations can be derived from thestructure of the maturity levels. This decomposition also indicates theprocesses and their structure that characterizes software process maturityand software process capability.

    3.1 Internal Structure of the Maturity Levels

    Each maturity level has been decomposed into constituent parts. With theexception of Level 1, the decomposition of each maturity level ranges fromabstract summaries of each level down to their operational definition in thekey practices, as shown in Figure 3.1. Each maturity level is composed ofseveral key process areas. Each key process area is organized into five

    CMU/SEI-93-TR-24 Capability Maturity Model 27

  • Operational Definition of the Capability Maturity Model

    sections called common features. The common features specify the keypractices that, when collectively addressed, accomplish the goals of the keyprocess area.

    28 Capability Maturity Model CMU/SEI-93-TR-24

  • Operational Definition of the Capability Maturity Model

    Maturity Levels

    KeyPractices

    contain

    contain

    Key Process Areas

    Implementation orInstitutionalization

    Goals

    Process Capability

    describe

    achieve

    indicate

    organized by

    CommonFeatures

    address

    Infrastructure orActivities

    Figure 3.1 The CMM Structure

    CMU/SEI-93-TR-24 Capability Maturity Model 29

  • Operational Definition of the Capability Maturity Model

    3.2 Maturity Levels

    A maturity level is a well-defined evolutionary plateau toward achieving amature software process. Each maturity level indicates a level of processcapability, as was illustrated in Figure 2.1. For instance, at Level 2 theprocess capability of an organization has been elevated from ad hoc todisciplined by establishing sound project management controls.

    3.3 Key Process Areas

    Except for Level 1, each maturity level is decomposed into several keyprocess areas that indicate the areas an organization should focus on toimprove its software process. Key process areas identify the issues thatmust be addressed to achieve a maturity level.

    Each key process area identifies a cluster of related activities that, whenperformed collectively, achieve a set of goals considered important forenhancing process capability. The key process areas have been defined toreside at a single maturity level as shown in Figure 3.2. The path toachieving the goals of a key process area may differ across projects based ondifferences in application domains or environments. Nevertheless, all thegoals of a key process area must be achieved for the organization to satisfythat key process area. When the goals of a key process area are accomplishedon a continuing basis across projects, the organization can be said to haveinstitutionalized the process capability characterized by the key process area.

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  • Operational Definition of the Capability Maturity Model

    Quality managementProcess measurement and analysis

    Initial (1)

    Repeatable (2) Software configuration management Software quality assurance Software subcontract management Software project tracking and oversight Software project planningRequirements management

    Defined (3)

    Peer reviews Intergroup coordination Software product engineering Integrated software management Training program Organization process definitionOrganization process focus

    Managed (4)

    Process change management Technology change managementDefect prevention

    Optimizing (5)

    Software quality management Quantitative process management

    Figure 3.2 The Key Process Areas by Maturity Level

    CMU/SEI-93-TR-24 Capability Maturity Model 31

  • Operational Definition of the Capability Maturity Model

    The adjective "key" implies that there are process areas (and processes) thatare not key to achieving a maturity level. The CMM does not describe allthe process areas in detail that are involved with developing andmaintaining software. Certain process areas have been identified as keydeterminers of process capability; these are the ones described in the CMM.

    Although other issues affect process performance, the key process areas wereidentified because of their effectiveness in improving an organization'ssoftware process capability. They may be considered the requirements forachieving a maturity level. Figure 3.2 displays the key process areas for eachmaturity level. To achieve a maturity level, the key process areas for thatlevel must be satisfied. To satisfy a key process area, each of the goals for thekey process area must be satisfied. The goals summarize the key practices ofa key process area and can be used to determine whether an organization orproject has effectively implemented the key process area. The goals signifythe scope, boundaries, and intent of each key process area.5

    The specific practices to be executed in each key process area will evolve asthe organization achieves higher levels of process maturity. For instance,many of the project estimating capabilities described in the Software ProjectPlanning key process area at Level 2 must evolve to handle the additionalproject data available at Levels 3, 4, and 5. Integrated Software Managementat Level 3 is the evolution of Software Project Planning and Software ProjectTracking and Oversight at Level 2 as the project is managed using a definedsoftware process.

    The key process areas of the CMM represent one way of describing howorganizations mature. These key process areas were defined based on manyyears of experience in software engineering and management and over fiveyears of experience with software process assessments and softwarecapability evaluations.

    5 For a listing of the goals for each key process area, refer to Appendix A.

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  • Operational Definition of the Capability Maturity Model

    The key process areas at Level 2 focus on the software project's concernsrelated to establishing basic project management controls. Descriptions ofeach of the key process areas for Level 2 are given below:

    The purpose of Requirements Management is to establish a commonunderstanding between the customer and the software project of thecustomer's requirements that will be addressed by the software project.This agreement with the customer is the basis for planning (asdescribed in Software Project Planning) and managing (as described inSoftware Project Tracking and Oversight) the software project. Controlof the relationship with the customer depends on following aneffective change control process (as described in Software ConfigurationManagement).

    The purpose of Software Project Planning is to establish reasonableplans for performing the software engineering and for managing thesoftware project. These plans are the necessary foundation formanaging the software project (as described in Software ProjectTracking and Oversight). Without realistic plans, effective projectmanagement cannot be implemented.

    The purpose of Software Project Tracking and Oversight is to establishadequate visibility into actual progress so that management can takeeffective actions when the software project's performance deviatessignificantly from the software plans.

    The purpose of Software Subcontract Management is to select qualifiedsoftware subcontractors and manage them effectively. It combines theconcerns of Requirements Management, Software Project Planning,and Software Project Tracking and Oversight for basic managementcontrol, along with necessary coordination of Software QualityAssurance and Software Configuration Management, and applies thiscontrol to the subcontractor as appropriate.

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  • Operational Definition of the Capability Maturity Model

    The purpose of Software Quality Assurance is to provide managementwith appropriate visibility into the process being used by the softwareproject and of the products being built. Software Quality Assurance isan integral part of most software engineering and managementprocesses.

    The purpose of Software Configuration Management is to establish andmaintain the integrity of the products of the software projectthroughout the project's software life cycle. Software ConfigurationManagement is an integral part of most software engineering andmanagement processes.

    The key process areas at Level 3 address both project and organizationalissues, as the organization establishes an infrastructure that institutionalizeseffective software engineering and management processes across allprojects. Descriptions of each of the key process areas for Level 3 are givenbelow:

    The purpose of Organization Process Focus is to establish theorganizational responsibility for software process activities thatimprove the organization's overall software process capability. Theprimary result of the Organization Process Focus activities is a set ofsoftware process assets, which are described in Organization ProcessDefinition. These assets are used by the software projects, as isdescribed in Integrated Software Management.

    The purpose of Organization Process Definition is to develop andmaintain a usable set of software process assets that improve processperformance across the projects and provide a basis for cumulative,long-term benefits to the organization. These assets provide a stablefoundation that can be institutionalized via mechanisms such astraining, which is described in Training Program.

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  • Operational Definition of the Capability Maturity Model

    The purpose of Training Program is to develop the skills andknowledge of individuals so they can perform their roles effectivelyand efficiently. Training is an organizational responsibility, but thesoftware projects should identify their needed skills and provide thenecessary training when the project's needs are unique.

    The purpose of Integrated Software Management is to integrate thesoftware engineering and management activities into a coherent,defined software process that is tailored from the organization'sstandard software process and related process assets, which aredescribed in Organization Process Definition. This tailoring is based onthe business environment and technical needs of the project, asdescribed in Software Product Engineering. Integrated SoftwareManagement evolves from Software Project Planning and SoftwareProject Tracking and Oversight at Level 2.

    The purpose of Software Product Engineering is to consistentlyperform a well-defined engineering process that integrates all thesoftware engineering activities to produce correct, consistent softwareproducts effectively and efficiently. Software Product Engineeringdescribes the technical activities of the project, e.g., requirementsanalysis, design, code, and test.

    The purpose of Intergroup Coordination is to establish a means for thesoftware engineering group to participate actively with the other engineeringgroups so the project is better able to satisfy the customer's needs effectivelyand efficiently. Intergroup Coordination is the interdisciplinary aspect ofIntegrated Software Management that extends beyond software engineering;not only should the software process be integrated, but the softwareengineering group's interactions with other groups must be coordinated andcontrolled.

    The purpose of Peer Reviews is to remove defects from the softwarework products early and efficiently. An important corollary effect is to

    CMU/SEI-93-TR-24 Capability Maturity Model 35

  • Operational Definition of the Capability Maturity Model

    develop a better understanding of the software work products and ofthe defects that can be prevented. The peer review is an important andeffective engineering method that is called out in Software ProductEngineering and that can be implemented via Fagan-style inspections[Fagan86], structured walkthroughs, or a number of other collegialreview methods [Freedman90].

    The key process areas at Level 4 focus on establishing a quantitativeunderstanding of both the software process and the software work productsbeing built. The two key process areas at this level, Quantitative ProcessManagement and Software Quality Management, are highlyinterdependent, as is described below:

    The purpose of Quantitative Process Management is to control theprocess performance of the software project quantitatively. Softwareprocess performance represents the actual results achieved fromfollowing a software process. The focus is on identifying special causesof variation within a measurably stable process and correcting, asappropriate, the circumstances that drove the transient variation tooccur. Quantitative Process Management adds a comprehensivemeasurement program to the practices of Organization ProcessDefinition, Integrated Software Management, Intergroup Coordination,and Peer Reviews.

    The purpose of Software Quality Management is to develop aquantitative understanding of the quality of the project's softwareproducts and achieve specific quality goals. Software QualityManagement applies a comprehensive measurement program to thesoftware work products described in Software Product Engineering.

    The key process areas at Level 5 cover the issues that both the organizationand the projects must address to implement continuous and measurablesoftware process improvement. Descriptions of each of the key process areasfor Level 5 are given below:

    36 Capability Maturity Model CMU/SEI-93-TR-24

  • Operational Definition of the Capability Maturity Model

    The purpose of Defect Prevention is to identify the causes of defects andprevent them from recurring. The software project analyzes defects,identifies their causes, and changes its defined software process, as isdescribed in Integrated Software Management. Process changes ofgeneral value are transitioned to other software projects, as is describedin Process Change Management.

    The purpose of Technology Change Management is to identifybeneficial new technologies (i.e., tools, methods, and processes) andtransfer them into the organization in an orderly manner, as isdescribed in Process Change Management. The focus of TechnologyChange Management is on performing innovation efficiently in anever-changing world.

    The purpose of Process Change Management is to continually improvethe software processes used in the organization with the intent ofimproving software quality, increasing productivity, and decreasing thecycle time for product development. Process Change Managementtakes the incremental improvements of Defect Prevention and theinnovative improvements of Technology Change Management andmakes them available to the entire organization.

    3.4 Common Features

    For convenience, the key process areas are organized by common features.The common features are attributes that indicate whether theimplementation and institutionalization of a key process area is effective,repeatable, and lasting. The five common features are listed below:

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  • Operational Definition of the Capability Maturity Model

    Commitment toPerform

    Commitment to Perform describes the actions theorganization must take to ensure that the process isestablished and will endure. Commitment to Performtypically involves establishing organizational policies andsenior management sponsorship.

    Ability to Perform Ability to Perform describes the preconditions that mustexist in the project or organization to implement thesoftware process competently. Ability to Perform typicallyinvolves resources, organizational structures, andtraining.

    ActivitiesPerformed

    Activities Performed describes the roles and proceduresnecessary to implement a key process area. ActivitiesPerformed typically involve establishing plans andprocedures, performing the work, tracking it, and takingcorrective actions as necessary.

    Measurement andAnalysis

    Measurement and Analysis describes the need to measurethe process and analyze the measurements. Measurementand Analysis typically includes examples of themeasurements that could be taken to determine the statusand effectiveness of the Activities Performed.

    VerifyingImplementation

    Verifying Implementation describes the steps to ensurethat the activities are performed in compliance with theprocess that has been established. Verification typicallyencompasses reviews and audits by management andsoftware quality assurance.

    38 Capability Maturity Model CMU/SEI-93-TR-24

  • Operational Definition of the Capability Maturity Model

    The practices in the common feature Activities Performed describe whatmust be implemented to establish a process capability. The other practices,taken as a whole, form the basis by which an organization caninstitutionalize the practices described in the Activities Performed commonfeature.

    3.5 Key Practices

    Each key process area is described in terms of the key practices thatcontribute to satisfying its goals. The key practices describe theinfrastructure and activities that contribute most to the effectiveimplementation and institutionalization of the key process area.

    Each key practice consists of a single sentence, often followed by a moredetailed description, which may include examples and elaboration. Thesekey practices, also referred to as the top-level key practices, state thefundamental policies, procedures, and activities for the key process area.The components of the detailed description are frequently referred to assubpractices. Figure 3.3 provides an example of the structure underlying akey practice for the Software Project Planning key process area.

    CMU/SEI-93-TR-24 Capability Maturity Model 39

  • Operational Definition of the Capability Maturity Model

    address

    Implementation or Institutionalization:

    Implementation

    Level 2, Repeatable

    contains

    disciplined process

    achieves

    indicates

    Software Project Planning

    Key Process Area:

    Goal 1:

    Process Capability:

    Maturity Level:

    Software estimates are documented for use in planning and tracking the

    software project. Activities Performed

    Common Feature:

    organized by

    Activity 9. Estimates for the size of the software work products (or changes to the size of software work products) are derived

    according to a documented procedure.

    Key Practice:

    Infrastructureor Activities:

    Activity

    contains

    describes

    Figure 3.3 Building the CMM Structure: An Example of a Key Practice

    40 Capability Maturity Model CMU/SEI-93-TR-24

  • Operational Definition of the Capability Maturity Model

    As illustrated in Figure 3.3, to ensure consistent accomplishment of the goalof documenting plans for planning and tracking the project, theorganization must establish a documented procedure for deriving estimatesof software size. If these estimates are not developed from a documentedprocedure, they may vary wildly as differences in sizing assumptions arenever surfaced. The detailed description of what would be expected in sucha procedure includes using historical size data, documenting assumptions,and reviewing the estimates. These criteria guide the judgment of whethera reasonable size estimating procedure is followed.

    The key practices describe "what" is to be done, but they should not beinterpreted as mandating "how" the goals should be achieved. Alternativepractices may accomplish the goals of the key process area. The key practicesshould be interpreted rationally to judge whether the goals of the keyprocess area are effectively, although perhaps differently, achieved. The keypractices are contained in the "Key Practices of the Capability MaturityModel, Version 1.1" [Paulk93b], along with guidance on their interpretation.

    CMU/SEI-93-TR-24 Capability Maturity Model 41

  • Operational Definition of the Capability Maturity Model

    42 Capability Maturity Model CMU/SEI-93-TR-24

  • 4 Using the CMM

    The CMM establishes a set of public in available criteria describing thecharacteristics of mature software organizations. These criteria can be usedby organizations to improve their processes for developing and maintainingsoftware, or by government or commercial organizations to evaluate therisks of contracting a software project to a particular company.

    This chapter focuses on two SEI-developed methods for appraising thematurity of an organization's execution of the software process: softwareprocess assessment and software capability evaluation.

    Software process assessments are used to determine the state of anorganization's current software process, to determine the high-priority software process-related issues facing an organization, and toobtain the organizational support for software process improvement.

    Software capability evaluations are used to identify contractors whoare qualified to perform the software work or to monitor the state ofthe software process used on an existing software effort.

    This overview is not sufficient by itself for readers to conduct either anassessment or evaluation. Anyone wishing to apply the CMM throughthese methods should request further information on assessment andevaluation training.

    The CMM is a common foundation for both software process assessmentsand software capability evaluations. The purpose of the methods are quitedifferent, however, and there are significant differences in the specificmethods used. Both are based on the model and the products derived fromit. The CMM, in conjunction with the CMM-based products, enables themethods to be applied reliably and consistently.

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  • Using the CMM

    4.1 Software Process Assessment and SoftwareCapability Evaluation Methods

    Software process assessments focus on identifying improvement prioritieswithin an organization's own software process. Assessment teams use theCMM to guide them in identifying an