# Decoding Information Flows: A Comprehensive Guide to Creating and Interpreting Sankey Charts
Sankey charts — a visual representation where flows between variables are depicted by way of arrows with widths representing magnitude — are a powerful tool when it comes to understanding the dynamics of information, material, or energy flows. With their ability to show how data moves from one point to another, these charts provide an unparalleled insight into complex information processes and decision-making pathways.
## What Are Sankey Charts?
**Sankey charts** are named after Matthew Henry Phineas Riall Sankey, an English engineer who employed them in the late 19th century to illustrate energy consumption on steam engines. Since then, they have been adapted in various fields for visualizing the flow of resources — financial, human, or data.
A **Sankey diagram** comprises nodes and links. Nodes represent entities (e.g., data sources, decision points, or actions), while links (arrows) illustrate the flow of data between these entities. The width of each link is proportional to the volume of data it carries.
## How to Create Sankey Charts
Creating a Sankey chart involves a few key steps:
### **Gather Data**
The first step towards creating a Sankey chart is to collect and organize your data. Data about the sources, destinations, and flows between these points are essential. Ensure all variables and quantities are accurately measured and labeled.
### **Choose Your Visualization Software**
Select a tool or software that supports Sankey diagrams, such as Tableau, Microsoft Power BI, Qlik, or online platforms like Sankeyviz and D3.js for custom builds. Each tool offers unique features, ease of use, and integration capabilities.
### **Define the Nodes and Links**
Nodes define the starting and ending points of your flows. Each node must have a unique identifier and label. Links, or the arrow-like connections, should map out the flow from one node to another.
### **Assign Widths to Links**
The size of the links reflects the volume of data flowing between each pair of nodes. This visual cue is critical in conveying the comparative intensity of flow directions.
### **Implement Additional Features**
Most software allows for customizing colors, transparency, text labels, and tooltips to enhance readability and provide additional information about each node or link. Adjust these settings based on your specific data and chart goals.
### **Review and Refine**
After creating the initial chart, critically review its clarity and effectiveness. Adjust the width, color schemes, and labeling to highlight key insights or trends. Refinement can make a significant difference in interpreting the data accurately.
## Best Practices for Interpreting Sankey Charts
### **Start with the Context**
Before interpreting a Sankey chart, ensure you fully understand the context in which it is presented. Are these data representing material use, financial transactions, data flows, or something else entirely? The context significantly influences how you should analyze the chart.
### **Focus on Flow Dynamics**
Unlike a network or flowchart, Sankey diagrams’ primary focus is on the distribution patterns of flow rather than decision paths. Look for clusters, dominant flows, and anomalies that could signal important patterns or areas needing further investigation.
### **Consider the Scale**
The scale of your Sankey diagram can significantly impact your interpretation. If the flows are disproportionately large or small, this might indicate a key bottleneck or highly relevant channel in your data.
### **Look for Correlations**
Examine how different nodes interact. High-impact flows (bigger links) between certain nodes (even if those nodes are not the most numerous or largest) can indicate significant relationships or impacts in the system being studied.
### **Utilize tooltips and labels**
Tooltips and node labels provide direct access to information not visible at first glance. They can clarify why certain flows are the way they are, or indicate if a high flow is anomalous within the context of other flows.
## Conclusion
Sankey charts offer deep insights into the movement, interactions, and distribution of flows within any system. By meticulously creating these diagrams and carefully interpreting the data they represent, stakeholders can uncover opportunities, risks, and insights that traditional reports or charts might overlook. Whether navigating complex data ecosystems, managing resources efficiently, or optimizing operations, the strategic use of Sankey charts can serve as a powerful analytical asset, providing clarity through visual understanding.
