Although it may seem like a simple decision, the success of a project depends on a broad range of factors, which all need careful consideration. For example, should an adaptive (value-driven, agile) approach be taken or a predictive one (plan-driven, waterfall)? Other factors include the anticipated volume and frequency of requirement changes, the nature of the environment within which the project will be delivered, the skills set and experience of the team that will deliver the project and the external dependencies of the project and organisation as a whole.
The anticipated volume and frequency of requirement changes are often a good indicator as to whether a firm should take an adaptive or predictive approach. If the volume and frequency are likely to be low, then a predictive approach may be suitable. If frequent changes in requirements are expected then an adaptive approach will probably be more successful as this is better suited to environments that require flexibility.