According to the PMI Guide to Business Analysis, a context diagram is a model that shows the boundaries of an area of analysis, such as a project, a system, a process, or an organization. A context diagram depicts the main entities or actors involved in the area of analysis, and the interactions or data flows between them. A context diagram can help to ensure the most effective representation of analysis boundary, as it provides a high-level overview of the scope and context of the area of analysis, and helps to identify the key stakeholders and their relationships. A context diagram can also help to communicate and validate the scope and context with the stakeholders, and to identify any assumptions or risks related to the area of analysis. A data flow diagram, a state diagram, and an entity relationship diagram are other models that can help to analyze an area of analysis, but they do not necessarily show the boundary or scope of it. References: PMI Guide to Business Analysis, page 158-159.