A simple question, is PMBOK a methodology? The answer is, and always will be, no. The acronym PMBOK refers to the Project Management Body of Knowledge; it is an evolving body of knowledge for the field of project management. PMBOK is centered on the Project Manager and the PMP Exam is an attempt to measure the knowledge of a Project Manager. This is quite different than a methodology. However, the importance of PMBOK to the profession of Project Management cannot be understated, as the knowledge contained within it can be leveraged by any formalized methodology. As such, it should be seen as complimentary to any project management method.
PRINCE2, Waterfall, and Agile are project management methodologies, each with different themes, principles, and processes. So why does this matter? For starters, a project management methodology is a step by step method for managing a project. It provides the Project Manager with a proven framework, guiding principles, and standardized templates for managing a project. The idea is to be able to apply established methods for successfully managing a project. The mechanics among methodologies will differ, but the end goal remains the same; bring the project in on budget, in scope, and within the specified time frame while meeting all stated Project Goals and Objectives.
The PRINCE2 Methodology was developed by the UK Office of Government Commerce (OGC) and is administered by APMG for certification. It is a generic methodology, which separates Management and Specialist Products. For those who have never studied PRINCE2, this may not make much sense. However, it’s a fairly simple concept. Specialist Products refer to areas of specialization, such as Software Application Development, Engineering, or Construction. For example, a project can be run utilizing the PRINCE2 Methodology, while using SCRUM as the methodology for the development of the product (such as a software application). A Management Product may include something like a Business Case, the initial assessment and continued justification for the development of that same software application. The PRINCE2 Methodology prides itself on its compatibility with other methods, and this is viewed as one of its primary strengths.
The Waterfall Methodology for project management has somewhat of a murky history as to its conception. However, it is probably the oldest formal Project Management Methodology in use today. The term Waterfall refers to the sequential nature of project phases, with each phase starting as another ends. There are supporters and critics of this approach to Project Management. Critics, especially in the Software Application Development domain, argue the excessive usage of documentation, planning, and up front design requirements are excessive and not compatible with real life situations (such as consistent changes to requirements based on evolving Stakeholder needs). This criticism does have merit, however champions of this methodology will point out the time and cost savings associated with thoroughly documenting requirements early in the Project Life Cycle. Supporters of this methodology will also point out that being thorough in documentation is good practice, especially in highly regulated industries. The primary means for dealing with the inevitable changes to requirements is a fully defined and implemented Change Management process. This is definitely a strong suit of the Waterfall Method, documenting and tracing all requirements back to the Business Need in a formalized fashion.
The Agile Methodology has been in practice for a while now, the actual “Agile Manifesto” was written in 2001. The overall goal of the Agile Methodology was to produce software applications in the most effective and efficient manner possible. While light on the documentation emphasis, Agile favors time-boxed efforts in producing application components; these are usually referred to as “Sprints.” This requires a highly skilled and close-knit project team (including Subject Matter Experts and Stakeholders) to produce software applications in short time periods. Supporters will argue the effectiveness of the Agile Method is found in its flexibility in dealing with ever-changing Stakeholder requirements; this is an assumption in the Agile Method. This is also its main criticism against the Waterfall Methodology. Critics of the Agile Method will note that lean documentation is not always compatible with the regulatory environment of the project. For example, the Pharmaceutical Industry, regulated by the Food and Drug Administration, may require extensive documentation in terms of Requirements Traceability for compliance. The adoption of the Agile Method will continue to grow, so long as the project environment (especially in regards to Regulation and Compliance) will allow it.
So the question is, what methodology is right for your organization? The answer is it depends. If your organization is highly regulated, then Agile may not be suitable to meet stringent compliance standards for application development. If however, your focus is rapidly developing software in a less stringent regulatory environment, then Agile may be appropriate. The Waterfall Methodology may be appropriate for larger projects which require extensive documentation. If properly implemented with stringent Change Management, it can be highly effective in executing a project. PRINCE2 can be run in any organization, although it is typically utilized by Governments and Multinationals, in tandem with a specialist methodology; as it is meant to be complimentary and not a standalone methodology. In general, PRINCE2 is used for very large, high risk projects. Many organizations will utilize hybrid methodologies to execute a project. This is probably the most common approach, and will probably continue. This does require Project Managers and Project Teams to have a diverse background, with experience in multiple methodologies.