The Capability Maturity Model (CMM) (a registered service mark of Carnegie Mellon University, CMU) is a development model that was created after study of data collected from organizations that contracted with the U.S. Department of Defense, who funded the research. This model became the foundation from which CMU created the Software Engineering Institute (SEI). The term "maturity" relates to the degree of formality and optimization of processes, from ad hoc practices, to formally defined steps, to managed result metrics, to active optimization of the processes.
When the CMM is applied to an existing organization's software-development processes, it allows an effective approach toward improving them. Eventually it became clear that the model could be applied to other processes. This gave rise to a more general concept that is applied to business.
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The Capability Maturity Model (CMM) was originally developed as a tool for objectively assessing the ability of government contractors' processes to perform a contracted software project. The CMM is based on the process maturity framework first described in the 1989 book Managing the Software Process by Watts Humphrey. It was later published in a report in 1993 (Technical Report CMU/SEI-93-TR-024 ESC-TR-93-177 February 1993, Capability Maturity Model for Software, Version 1.1) and as a book by the same authors in 1995.
Though the CMM comes from the field of software development, it is also used as a general model to aid in improving organizational business processes in diverse areas; for example in software engineering, system engineering, project management, software maintenance, risk management, system acquisition, information technology (IT), services, business processes generally, and human capital management. The CMM has been used extensively worldwide in government offices, commerce, industry and software-development organizations.
In the 1960s, the use of computers grew more widespread, more flexible and less costly. Organizations began to adopt computerized information systems, and the demand for software development grew significantly. Many processes for software development were in their infancy, with few standard or "best practice" approaches defined.
As a result, the growth was accompanied by growing pains: project failure was common, and the field of computer science was still in its early years, and the ambitions for project scale and complexity exceeded the market capability to deliver adequate products within a planned budget. Individuals such as Edward Yourdon, Larry Constantine, Gerald Weinberg, Tom DeMarco, and David Parnas began to publish articles and books with research results in an attempt to professionalize the software-development processes.
In the 1980s, several US military projects involving software subcontractors ran over-budget and were completed far later than planned, if at all. In an effort to determine why this was occurring, the United States Air Force funded a study at the SEI.
The Quality Management Maturity Grid was developed by Philip B. Crosby in his book Quality is Free,[1] which advanced the position that quality-improvement activities paid for themselves by reducing the related costs.
The first application of a staged maturity model to IT was not by CMM/SEI, but rather by Richard L. Nolan, who, in 1973 published the stages of growth model for IT organizations.[2]
Watts Humphrey began developing his process maturity concepts during the later stages of his 27 year career at IBM.
Active development of the model by the US Department of Defense Software Engineering Institute (SEI) began in 1986 when Humphrey joined the Software Engineering Institute located at Carnegie Mellon University in Pittsburgh, Pennsylvania after retiring from IBM. At the request of the U.S. Air Force he began formalizing his Process Maturity Framework to aid the U.S. Department of Defense in evaluating the capability of software contractors as part of awarding contracts.
The result of the Air Force study was a model for the military to use as an objective evaluation of software subcontractors' process capability maturity. Humphrey based this framework on the earlier Quality Management Maturity Grid developed by Philip B. Crosby in his book "Quality is Free".[1] However, Humphrey's approach differed because of his unique insight that organizations mature their processes in stages based on solving process problems in a specific order. Humphrey based his approach on the staged evolution of a system of software development practices within an organization, rather than measuring the maturity of each separate development process independently. The CMM has thus been used by different organizations as a general and powerful tool for understanding and then improving general business process performance.
Watts Humphrey's Capability Maturity Model (CMM) was published in 1988[3] and as a book in 1989, in Managing the Software Process.[4]
Organizations were originally assessed using a process maturity questionnaire and a Software Capability Evaluation method devised by Humphrey and his colleagues at the Software Engineering Institute (SEI).
The full representation of the Capability Maturity Model as a set of defined process areas and practices at each of the five maturity levels was initiated in 1991, with Version 1.1 being completed in January 1993.[5] The CMM was published as a book[6] in 1995 by its primary authors, Mark C. Paulk, Charles V. Weber, Bill Curtis, and Mary Beth Chrissis.
The CMM model proved useful to many , but its application in software development has sometimes been problematic. Applying multiple models that are not integrated within and across an organization could be costly in training, appraisals, and improvement activities. The Capability Maturity Model Integration (CMMI) project was formed to sort out the problem of using multiple models for software development processes, thus the CMMI model has superseded the CMM model, though the CMM model continues to be a general theoretical process capability model used in the public domain.
The CMM was originally intended as a tool to evaluate the ability of government contractors to perform a contracted software project. Though it comes from the area of software development, it can be, has been, and continues to be widely applied as a general model of the maturity of process (e.g., IT service management processes) in IS/IT (and other) organizations.
A maturity model can be viewed as a set of structured levels that describe how well the behaviors, practices and processes of an organization can reliably and sustainably produce required outcomes. A maturity model may provide, for example :
A maturity model can be used as a benchmark for comparison and as an aid to understanding - for example, for comparative assessment of different organizations where there is something in common that can be used as a basis for comparison. In the case of the CMM, for example, the basis for comparison would be the organizations' software development processes.
The Capability Maturity Model involves the following five aspects:
There are five levels defined along the continuum of the CMM and, according to the SEI: "Predictability, effectiveness, and control of an organization's software processes are believed to improve as the organization moves up these five levels. While not rigorous, the empirical evidence to date supports this belief".
Within each of these maturity levels are Key Process Areas (KPAs) which characterise that level, and for each KPA there are five definitions identified:
The KPAs are not necessarily unique to CMM, representing — as they do — the stages that organizations must go through on the way to becoming mature.
The CMM provides a theoretical continuum along which process maturity can be developed incrementally from one level to the next. Skipping levels is not allowed/feasible.
N.B.: The CMM was originally intended as a tool to evaluate the ability of government contractors to perform a contracted software project. It has been used for and may be suited to that purpose, but critics pointed out that process maturity according to the CMM was not necessarily mandatory for successful software development. There were/are real-life examples where the CMM was arguably irrelevant to successful software development, and these examples include many shrinkwrap companies (also called commercial-off-the-shelf or "COTS" firms or software package firms). Such firms would have included, for example, Claris, Apple, Symantec, Microsoft, and Lotus. Though these companies may have successfully developed their software, they would not necessarily have considered or defined or managed their processes as the CMM described as level 3 or above, and so would have fitted level 1 or 2 of the model. This did not - on the face of it - frustrate the successful development of their software.
At maturity level 5, processes are concerned with addressing statistical common causes of process variation and changing the process (for example, to shift the mean of the process performance) to improve process performance. This would be done at the same time as maintaining the likelihood of achieving the established quantitative process-improvement objectives.
The software process framework documented is intended to guide those wishing to assess an organization/projects consistency with the CMM. For each maturity level there are five checklist types:
| Type | Description |
|---|---|
| Policy | Describes the policy contents and KPA goals recommended by the CMM. |
| Standard | Describes the recommended content of select work products described in the CMM. |
| Process | Describes the process information content recommended by the CMM. The process checklists are further refined into checklists for:
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| Procedure | Describes the recommended content of documented procedures described in the CMM. |
| Level overview | Provides an overview of an entire maturity level. The level overview checklists are further refined into checklists for:
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