There are lot's of good sources showing how to write and handle requirements. But often they miss one important fact which makes either the creation, prioritization and understanding of requirements much easier. The Why instead of the What.
- First set the baseline for effectiveness. (Why)
- Than define what you need to be effective. (What)
- And at the end define the efficiency. (How)
What is the rational, the reason for a particular requirement. If you try to understand the Why or if you forced to define the Why the resulting requirements / usage of the requirement are much more valid than without doing this.
The "What" does not tell anyone the real intention of a solution. The why provides the motivation and business value and therefore the baseline for effectiveness which makes or makes not a requirement right to exists.
- Before you start to define any requirement try to define the major "Whys" you intent to solve. Keep in mind that there must no requirement which cannot be derived from those high level whys.
- derive each use-case / requirement from one of the major why areas and add a specific rational for the individual use-case / requirement.
- classify / prioritize the requirements based on the rational.
- Derive the "How". In this step the statement of efficiency is the key for selection of the right solution.
- The defined requirements are much easier to understand and alternatives can be much easier identified and qualified.
- Prioritization can be much easier coordinated to management because the consequence of a decision for the "Why" and therefore the company / department goals are always clear even if someone does not have detailed knowledge of the subject matter.
- Definition of the system requirements / How can focused on efficiency.