According to the PMBOK® Guide, project management involves iterative planning as more information becomes available. This specific iterative technique is formally known as rolling wave planning.
Rolling wave planning is a form of progressive elaboration where the work to be accomplished in the near term is planned in detail, while the work far in the future is planned at a higher level.
Mechanism: It is a functional application of the " progressive detailing " mentioned in the question. As the project progresses and more risks and requirements are identified, the " wave " moves forward, and the high-level plans are decomposed into detailed work packages.
Context: This is particularly useful in projects where the full scope is not entirely clear at the start (such as RandD or software development) or in high-uncertainty environments.
A. Expert judgment: This is a tool and technique used in almost every project management process. While experts may help with detailing a plan, " expert judgment " refers to the specialized knowledge or training used to make a decision, not the process of progressive detailing itself.
C. Work performance information: This is an output of various controlling processes (like Control Schedule or Control Costs). it is the processed data used to make decisions, but it is not a planning technique.
D. Specification: A specification is a document that describes the requirements, design, or behavior of a product or service. While a specification can be detailed progressively, it is a document/input, not the act of detailing the overall management plan.
Rolling wave planning is the primary technique used to achieve Progressive Elaboration. In the PMI framework, this acknowledges that as a project evolves, the project management team gains a better understanding of the objectives and deliverables, allowing them to manage the project with greater " granularity " over time.
