Methodologies – The Spiral Model

The Spiral model is a risk-oriented life cycle model that breaks down the development process into smaller phases. The objective of each phase is not only to address one or more of the major project risks, but also to focus and deliver on the high-level requirements first, and then, those that are less urgent in subsequent iterations.

The premise behind this model is to start in the middle, identify the risks, develop a plan to handle those risks and then commit to a solution. Each iteration moves the project to a larger scale.

This approach demonstrates progress and allows refining and understanding of the requirements with each iteration and implementation. This is particularly important when there are several approaches and solutions being brought together. It is important to complete each step in the Spiral model; however, they do not need to be completed in the order listed below.

Note: There are different iterations of the Spiral Model but most share similar core values.

The six main steps involved with each iteration are:
1. Determine objectives and deliverables, their alternatives, and constraints.
2. Risk Analysis: Identify and resolve risks.
3. Evaluate objectives, alternatives, and constraints.
4. Develop and verify that the deliverables for that iteration are correct.
5. Plan the next iteration.
6. Commit to an approach for the next iteration.