7.6.7 Goal Orientation and top-down analysis
Some people sometimes mistakenly believe that goal-oriented approaches are top-down approaches, where we start from very high-level goals and proceed by stepwise goal decomposition until the requirements are obtained.
This is by no means the case, of course; see Section 7.5. The material obtained from elicitation sessions most often covers a mix of strategic concerns, operational procedures, scenario examples, complaints, low-level details and so forth.
No RE process can be made linear. We need to backtrack on issues as risks, conflicts and other problems become apparent.
In order to build a complete, consistent and adequate picture of the system-to-be from tis hybrid and ill-assorted material, a goal-oriented approach must necessarily combine top-down and bottom-up processes driven by HOW and WHY question, respectively.