A design methodology is series of phases that guide a project lifecycle. Generally speaking there are an uncountable number of design methodologies, but the two most utilised are the predictive and the adaptive approach. The predicative approach assumes that a project can be planned in advance and the adaptive approach assumes the opposite. These design methodologies are also referred to as traditional or waterfall approach and spiral or iterative approach respectively.
The phases involved generally fall into the categories of planning, analysis, design, implementation and support. Whether implementing the predictive or adaptive approach, each phase is an important step in the design methodology but can differ depending on the approach taken. Additional, depending on the design methodology implemented, the phases may not exist as separate entities and can be combined, split up or even removed all together.
During the planning phase the problem and scope are defined, a work breakdown structure and schedule is developed, a feasibility study is undertaken, team members are assigned and official approval is sought for commencement.
The analysis phase involves gathering information relevant to the scope of the problem, constructing models or prototypes to assist information gathering, defining the goals or requirements and assessing and prioritising those goals or requirements. Information gathering techniques involve interviews, observation, reviewing industry standards, questionnaires, joint application design (JAD) sessions and general research.
The design phase includes designing and integrating the system controls, designing the system and designing the system interfaces.
The implementation phase involves constructing the system, verifying and testing the system, data conversion, training users, documenting the system and installation of the system.
Finally, the support phase encompasses maintenance of the system, improving the systems and providing continual support for users of the system.
The traditional or waterfall approach follows a sequential set of phases that need to be complete in order, one after the other. In most cases the waterfall approach does not contain overlapping phases and each phase must be completed before beginning the next phase. On the other hand, the adaptive approach involves repeating phases and/or overlapping phases. Usually the phases are repeated in a looping or spiral fashion but can also follow the more traditional linear pattern with overlap or loopbacks to only a few of the phases.
Design methodologies encompass not only how the project lifecycle is planned out but also the models, tools and techniques used to assist the project lifecycle. Models can include anything from diagrams and charts to real world representations and abstract representations. Tools range from simple programs to produce models to complex Computer Aided Software Engineering (CASE) tools. Finally, techniques consist of step-by-step instructions, guidelines or advice to assist the completion of the phases or the project lifecycle.
Design methodologies are mostly notably applied to project management and technological industries such as software development. In project management, design methodologies allow projects to be directed to achieve the expected goals within the given constraints. Technological industries also follow a very similar approach to project management.
Methodologies can also be applied to everyday tasks, especially within the area of business. In retail, staff are often given guidelines on how to deal with customer complaints. Most notably, ALARA involves the steps of acknowledge, listen, ask questions, recap and act. This is in essence a design methodology which begins with the planning phase (acknowledge), the analysis and design phase (listen and ask questions), the support phase (recap) and implementation phase (act).