Mastering Sankey Charts: A Comprehensive Guide to Visualizing Flow and Data Attribution
Sankey charts represent flows or streams of data or substance between points in a network. They are powerful tools for visualizing complex datasets by showing the magnitude and direction of flows.
In this guide, we will explore the fundamentals of Sankey charts, their types, applications, construction, and some best practices that will assist in enhancing data presentation and interpretation.
1. **Understanding Sankey Charts**
A Sankey diagram essentially shows the flow of quantities across different pathways. It utilizes arrows or lines to depict the streams and their magnitudes. These diagrams are named after Captain Matthew Henry Phineas Riall Sankey, an engineer who introduced this type of data visualization in the 19th century to illustrate the energy consumption of his factories.
Sankey charts are effective for visualizing data in energy consumption, traffic flow, money transactions, and many other areas that involve information pathways.
2. **Types of Sankey Charts**
There are mainly four types of Sankey diagrams:
**a. Simple Sankey Chart:** It involves two nodes, with arrows representing flow between them. Best for illustrating basic data flows.
**b. Compound Sankey Chart:** Features multiple connections or “links” within the same line node, indicating multiple flow paths between the same pair of nodes. Common for more complex datasets.
**c. Grouped Sankey Chart:** Represents each flow as a separate set of stacked nodes or flows, allowing the visualization of different ‘types’ of flow within the same source and destination.
**d. Circular Sankey Chart:** Uses a circle layout to display the flows, ideal for visualizing flows around a central entity.
3. **Construction of Sankey Charts**
To create an effective Sankey chart:
**a. Data Collection:** Identify your key data elements: sources, destinations, and flow quantities.
**b. Data Merging:** Merge related data elements so that all quantities are represented consistently.
**c. Node Creation:** Define your nodes as sources, destinations, or categories of sources and destinations.
**d. Line Creation:** Assign lines to represent flows. Width should reflect the magnitude of flow.
**e. Adjustment and Interactivity:** Optimize layouts for clarity and enable interactive features for deeper exploration.
4. **Best Practices**
– **Balanced Widths:** Ensure the widths of lines align with the value they represent, providing visual cues for magnitude differences.
– **Simplicity over Complexity:** Avoid overcrowding your Sankey chart with too many nodes or lines, which can make the visualization cluttered and hard to interpret.
– **Labeling Cleared:** Clearly label nodes and lines, but be mindful of not overwhelming the chart with text, potentially detracting from the visual clarity.
– **Consistent Scale:** Adopt a consistent color scheme that enhances readability and keeps the flow of understanding through the chart.
**Conclusion**
Mastering the Sankey chart is vital for data analysts, marketers, and information designers looking to explore and present complex data flows in an engaging and understandable manner. By understanding the types of Sankey charts, their construction methodology, and best practices, one can effectively communicate data pathways and attribution in fields ranging from environmental studies to business analytics.
Whether you’re working with energy consumption, traffic patterns, or supply chain logistics, the Sankey chart is a potent graphical tool offering insights at a glance.
