Decoding Complex Systems with Sankey Diagrams: An Essential Guide to Creating and Understanding Sankey Charts
Sankey diagrams, also known as Sankey flowcharts, are a type of data visualization used to represent flow patterns. These diagrams employ arrows to depict transfer of data, material, or energy, connecting nodes or points that symbolize components or stages in a system. In this article, we delve deep into the world of Sankey diagrams, providing an essential guide to understanding their structure and purpose, and the step-by-step process of creating them.
Understanding Sankey Diagrams
Sankey diagrams were first introduced by Captain Matthew Henry Phineas Riall in 1832 to map the energy consumption and use in a coal trade system. Since then, these diagrams have found numerous applications in various fields, from engineering, where they map processes or manufacturing flows, to business, where they illustrate supply chains and sales. Key features that characterize Sankey diagrams include:
1. **Nodes**: These represent the origin or end points of the flow. In process diagrams, for instance, nodes represent the start of a supply chain, a process step, or the end of a product lifecycle.
2. **Flows (Arrows)**: These depict the magnitude of data, material, or energy passing through from one node to another. The width of the arrow indicates the strength, magnitude, or amount of the flow.
3. **Labels**: These provide details about the nature of the flow, the units of measurement, or labels of the node.
Creating a Sankey Diagram
Creating a Sankey diagram involves a number of steps:
1. **Identify Your Data**: Gather the data you wish to illustrate. This could be the flow of material, data, money, or any quantifiable measure between different points in your system.
2. **Define Nodes and Categories**: Determine the nodes—each represents a station, process, or category where flow starts or ends. Each process or system must have a clear start point and an end point.
3. **Calculate Flow Values**: For each flow from source to destination, calculate the total amount of flow. This could be anything from miles of transportation, units of products, or money transferred.
4. **Analyze the Flows**: Look at the overall system and the specific flows to ensure that the flows are balanced. That is, the total flow into nodes must equal the total flows out from the nodes.
5. **Choose the Appropriate Software**: Utilize software or tools specifically designed to create Sankey diagrams. Tools like Microsoft PowerPoint, Adobe Illustrator, Visio, or more specialized tools such as Graphviz, SankeyDIAGRAM, and Microsoft Excel help in producing these diagrams.
6. **Create the Diagram**:
– Arrange the nodes (source, sink, and intermediate nodes) around the perimeter of the diagram.
– Connect the nodes with flows (arrows). The width of the arrows should represent the magnitude of the flow.
– Assign colors if there are distinct categories or processes you wish to differentiate.
7. **Review and Adjust**: After creating the initial diagram, review it to ensure clarity and accuracy. This might involve adjusting the sizes, colors, or other aesthetic elements, making changes in node labels or flow values, or verifying the completeness of the diagram.
8. **Finalize and Present**: Ensure your Sankey diagram is easily understandable for your audience. The final diagram should be clear, balanced, easy to read, and well-labeled. This can be printed or presented in a digital format.
Using Sankey Diagrams
Sankey diagrams are indispensable for understanding complex systems. They are particularly useful:
– **In Engineering**: To illustrate the flow of energy, materials, or data through manufacturing or mechanical processes.
– **In Business**: To reveal the distribution of money, costs, or revenue through supply chains or marketing funnels.
– **In Data Science**: To map data flow through datasets, explaining the origins and destinations of data in databases, web traffic, or predictive analytics models.
– **In Environmental Science**: For visual representation of energy distribution, material flow in ecosystems, or pollution dispersion.
By applying these elements in a thoughtful and strategic manner, Sankey diagrams can illuminate the intricate pathways and dynamics within the systems they depict, revealing insight and guiding decision-making processes. In conclusion, Sankey diagrams serve as a bridge between the abstract complexities of interconnected systems and the tangible, understandable information that helps us navigate and improve our world.
