Requirements in the Iterative Model

From the requirements management perspective, the iterative approach provides two major advantages.

1. Better adaptability to requirements change. The model recognizes that requirements change and requirements activities are therefore active throughout the lifecycle. Requirements are not frozen, they are understood early at a certain level of detail, and they are refined successively over time. And since they are revisited at every iteration, new requirements can be considered at each iteration.

2. Better scope management. If the first iteration is missed by 30 percent, that's an indicator that the project may be badly scoped, and adjustments can be made. Even if scope is not well managed, multiple executable iterations have been developed by the time the deadline is reached, and the last may even be deployable . Even though it lacks some functionality, the release will deliver value to the user if the features have been picked and prioritized carefully , allowing your customer to meet objectives, at least in part, as you continue with further development iterations. And, if the architecture is robust and addresses the key technical issues, your team will have a solid platform on which to base the additional functionality.

With this software process model in mind, we can move forward to the requirements activities that are pertinent to each phase in the lifecycle. Yet we also recognize that the point in the lifecycle in which an activity occurs is not fixed or predetermined, and indeed, the requirements activities can be revisited as necessary over time as our understanding of the system evolves.