| We’ve all seen instances where someone was making something up as they were going along. And the end result is usually not very good. It’s no different in the product development process. If an engineer designs a product without identifying all requirements, then the product may not meet the expectations of its end user. Worse yet, it may pose a hazard during use and open up a world of potential liabilities. There are three basic requirements for successful product development: functionality, performance, and constraint. A functional requirement specifies the necessary task, activity, or action that the product must be able to achieve. A performance requirement specifies how well the product must perform under specific conditions. A constraint requirement sets out the constraints under which the product must operate. An example would be compliance with government regulations and industry standards.
In every successful product development project the goal is to create requirements that are well defined, well specified, and traceable, meaning each requirement should include the name of its originator and a space for their signature, indicating approval. This eliminates any spinning-of-the-wheels due to misunderstandings, finger pointing, etc.
Well defined requirements are, of course, tied into specific design criteria and form the basis of a detailed design specification. These criteria guide the way through all stages of the product’s development. Each requirement should be listed, along with the rationale for its creation and a test method to verify that its objectives have been met.
Requirements are only good if they are achievable, verifiable, unambiguous, complete, expressed in terms of a need (not a solution), and consistent.
Otherwise, what’s the point?