According to the PMBOK Guide, a context diagram is a visual representation of the product scope, showing a business system (process, equipment, computer system, etc.), and how people and other systems (actors) interact with it. A context diagram can help the project manager and the key stakeholder to understand the project's key performance indicators (KPIs) and how they relate to the project objectives, scope, and deliverables. A context diagram can also help to identify the sources of data for the KPIs, the frequency of measurement, and the reporting format. A context diagram can facilitate communication and collaboration between the project manager and the key stakeholder, and help to resolve any issues or disagreements regarding the project's KPIs. Autocratic decision making, expert judgment, and change control tools are not appropriate tools or techniques for this situation, as they do not address the root cause of the stakeholder's dissatisfaction with the project's KPIs, and may create more conflict or resistance. References: PMBOK Guide, Sixth Edition, pages 154-155, 176; PMI-PBA Guide, First Edition, pages 97-98, 102.