Aspiring business analysts often ask, what is the most important diagram in business analysis?
While this question cannot have one straight definitive answer, as projects vary so much in size and scope, I will suggest here three diagrams that are needed on every project. They can be created relatively quickly and present a very good investment of time.
Of course, many projects, especially those touching multiple systems and business processes, will require much more than three simple and high-level diagrams. However, detailed modelling must be based on high-level models. Initial discovery sessions will go much better if supported by the same high-level pictures. Engaging stakeholders in the conversation and framing the conversation effectively can also benefit from these diagrams:
- Context model
- Business use case diagram
- High-level process flow
A context model describes the interfaces and connections of the business or system with the environment in which it exists.
Context models capture how the central object interacts with its environment, be it exchanging data, physical objects, or funds. Context models can be created for an enterprise, a system, or a process.
This example shows a system context model for a Package tracking system, demonstrating how context models can be used to capture the current state, the future state, and the scope of change (highlighted by using a color and a legend). In system context flows, the arrows represent integrations and flows of data or messages.
System context models support analysis by capturing other systems the solution interacts (or should interact) with, supporting impact analysis, data, and integration requirements.
A business use case diagram captures the actors that need the solution, and what they need to use it for.
The example below captures the scope of the Package Tracking System by showing how each actor (Sender, Receiver, Courier, Station Manager, etc.) will use the solution. These uses are represented as business use cases (Request pick-up, Track shipment, Deliver Shipment, Resolve customer dispute, etc.).
Just like with context models and other diagrams, a business use case diagram can depict the current state, future state, and the scope of change. These diagrams help identify key personas, user roles, and impacted departments, and capture the main functionality of the solution. Each business use case will translate into an epic or a group of requirements.
Process flows show the sequence of steps in a business process.
Just like other diagrams, they can be very detailed or high-level. A high-level process flow is crucial at the start of the project. Later, as the project develops, more detailed workflow analysis will require detailed process flows; however, a high-level depiction is useful from the start.
A sample high-level swim lane diagram below shows an end-to-end process. Each rectangles represents an essential step in the process (which can be broken down into more granular steps as the analysis gets into the details). At the start of the project, the high-level flow is useful for identifying the scope of change, how the change fits into the overall process, who is involved, and the sequence of activities.
This particular example also shows:
- How to include additional information such as where each activity is performed (in different applications or manually)
- How to highlight pain points
How are these diagrams connected?
They can build on each other and be used to validate each other. For example:
- The actors in the swimlanes may be represented as actors in the business use case diagram. Depending on the granularity, an actor in a swimlane may align with a department, an external organization, or a particular role such as an approver.
- A single business use case can be further captured as a process flow; or sometimes, a process flow will include two or three business uses, e.g., Assess custom duties, Pay custom duties, and Deliver Shipment.
- While all external entities captured in a context model are unlikely to show up in one process flow, a process flow may involve a subset of these external entities. E.g., “System B” in this process flow may represent the Notification platform from the context model. Working on process flow diagrams with stakeholders can help business analysts uncover additional entities that the solution will interact with, to be added to the context model.
- An entity from a context model may be represented by one or more actors in the business use diagram. For example, the Customs officer from the business use diagram belongs to the Customs office from the context model, while the Courier may use both the Package Tracking system and the Courier app captured in the context model.
All these relationships help capture the scope of change and future solution from different perspectives, complementing each other.
All three diagrams should be part of any business analyst’s toolkit.
If you want to add them to yours, check out my BA Portfolio Building Course (Part I) that covers all these diagrams, RACI matrix, requirements starter matrix, and stakeholder register. If you are looking for templates, get my BA Playbook that includes a broad selection of artifacts needed on different projects.
Read more:
A Context Model in 5 Minutes (video)
Context Model Example: Daycare
Expanding the Use of a Use Case Diagram
How to Create Business Use Case Diagrams (video)
Use Case Diagrams and How To Use Them (video)
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