In order to ensure higher commitment levels, estimates should be created, or approved by:

When the person who will actually perform the work creates or approves the estimate, they develop a sense of ownership and accountability, leading to more realistic estimates and a higher commitment to achieving those estimates. This bottom-up approach leverages expert knowledge and encourages responsibility.

The customer defines requirements but is not directly responsible for the work execution and therefore cannot provide accurate estimates or commit to performing the work.

While the project manager facilitates the estimating process, they typically do not have the detailed task-level knowledge to create accurate estimates for all work packages themselves.

Key stakeholders have an interest in the project outcome but are usually not the ones performing the detailed tasks, making their estimates less reliable for commitment purposes.