During the project, requirements change for a variety of reasons. As needs change and as work proceeds, additional requirements are derived and changes may have to be made to the existing requirements. It is essential to manage these additions and changes efficiently and effectively. To effectively analyze the impact of the changes, it is necessary that the source of each requirement is known and the rationale for any change is documented. The project manager may, however, want to track appropriate measures of requirements volatility to judge whether new or revised（）are necessary.

The receiving activities conduct analyses of the requirements with the requirements provider to ensure that a compatible, shared understanding is reached on the meaning of the requirements. The result ofthis analysis and dialog is an（）set of requirements.

（）involves using mathematical techniques to forecast future outcomes based onhistorical results.

Performing（）involves monitoring specific project results to determine if they comply with relevant quality standards and identifying ways to eliminate causes of unsatisfactory results.

The project（）is a key input to quality planning since it documents major project deliverables, the project objectives that serve to define important stakeholder requirements,thresholds, and acceptance criteria.