A project's customer is furious.

When a customer discovers that one of their requirements was not met, the project manager should refer to the requirements traceability matrix (RTM) to analyze the requirement in question. The RTM is a tool that links product requirements from their origin to the deliverables that satisfy them. It helps ensure that all requirements are accounted for and that any changes or updates to the requirements are properly managed throughout the project lifecycle. By analyzing the RTM, the project manager can identify where the breakdown occurred and take corrective action to address the customer’s concern1. References: = Requirement Traceability: A Tool for Quality Results | PMI1.