The project manager should validate against the scope statement and ask for sign-off after a system was implemented and testing was successfully completed. The scope statement is a document that defines and documents the project scope, objectives, deliverables, requirements, assumptions, and constraints. The scope statement can help to establish a common understanding and agreement between the project manager and the stakeholders on what the project aims to achieve and deliver. Validating against the scope statement means checking whether the project deliverables meet the agreed-upon scope criteria and quality standards. Asking for sign-off means requesting formal acceptance and approval of the project deliverables from the stakeholders.