One of the most important decisions in requirements writing is first being sure a requirement is even necessary.
Some experts on the topic recommend asking yourself what is the worst thing that can happen without a particular requirement. If the answer is “nothing much,” then a requirement probably isn’t needed.
When a specific requirement is needed, it must also be attainable. To be attainable, the requirement must be technically feasible and fit within budget, schedule and other constraints. If you are uncertain about whether a requirement is technically feasible, a study may be required to determine its feasibility.
If what you want is not technically feasible or not within budget restraints, it’s no longer a requirement but rather a goal.
In requirements writing (as in good writing in general), authors should strive for clarity. Each requirement should express a single thought, be concise, and simple. It is important that the requirement not be misunderstood — it must be unambiguous. Simple sentences will most often suffice for a good requirement.
It’s important to avoid over-specification. The Department of Defense (DoD) has gone on record as admitting that over-specification is the primary cause of cost overruns in their programs. Over-specifying is most often from stating something that is unnecessary or from stating overly stringent requirements.
Requirements writers should write down everything that comes to mind followed by a careful review of each requirement focusing on why it is needed before base lining the specification.
One important tip is to remember to use the word “shall.” Shall is the traditional keyword for identifying a functional requirement. Functional requirements describe behaviors the system shall exhibit under certain circumstances or actions the system shall let the user take.
Some people object to the use of shallbecause it feels stilted. However, using a distinctive word like “shall” clearly distinguishes a requirement from other information in a specification.
Want to learn more? Tonex offers Requirements Writing Training Course — Specification Writing Training, a 2-day course that shows you how to write well-formed, validated requirements and specifications.
This is an excellent course for project stakeholders, SMEs, directors, project sponsors, users and just about anyone involved in the planning and writing of specifications requirements.
For more information, questions, comments, Contact us.