# Decoding Complex Flows: A Comprehensive Guide to Creating and Interpreting Sankey Charts
Sankey charts, a type of flow diagram, are used to visualize the movement and distribution of quantities between different sources and sinks. Named after the Scottish engineer Matthew Henry Phineas Riall Sankey, who pioneered their use, these charts have become an essential tool for understanding complex systems across various fields, including economics, environment, urban planning, and more. In this guide, we will explore the principles behind sankey charts, how to create them, and how to interpret the flow data to extract meaningful insights.
## What are Sankey Charts?
Sankey diagrams, named after the Scottish mechanical engineer Matthew Sankey, represent the flow of quantities between different sources and sinks. They consist of nodes (representing categories or stages) and flows (the connecting lines that represent connections between these nodes), with the width of the lines proportional to the flow quantity. This makes it easy to see at a glance which movements are the largest, where more can be produced or consumed, and which parts of the overall flow are most significant (or insignificant).
## Creating Sankey Charts
### Step 1: Identify the Flow
The first step in creating a sankey chart is identifying the flow you want to visualize. This could be anything from sales data between different regions in a company to energy consumption patterns in a city. Ensure there are clear sources (inputs) and sinks (outputs) in your data.
### Step 2: Prepare Your Data
Organize your data with categories for the sources and sinks, and quantities for the different flows between them. This data is the foundation of your sankey chart. Each value you have will correspond to the width of the lines connecting the nodes.
### Step 3: Choose a Tool
You can create sankey charts using various software tools, such as:
– **Microsoft Excel**: With add-ons like “Flow Chart Tools” which allow the creation of sankey diagrams.
– **PowerBI**: Offers tools for creating and customizing sankey diagrams.
– **Datawrapper**: Provides a simpler interface for users who prefer web-based tools.
– **R & Python with Packages like `sankeychart` or `plotly`**: Recommended for users familiar with programming, allowing for more complex customizations.
– **DIY Sankey Chart Creator**: Online tools or software that require no coding knowledge to build sankey diagrams.
### Step 4: Design Your Chart
Customize the look of your sankey chart to ensure clarity and readability. This includes adjusting colors, line thickness (representing the flow magnitude), and text labels to ensure that each flow is easily comprehensible.
### Step 5: Add Additional Elements
For clarity, you can include:
– **Title**: Describing the overall purpose of the chart.
– **Subtitle**: Briefly explaining the data or key information.
– **Legends**: If your chart uses different colors for different categories.
– **Annotations**: To highlight key insights or important data points.
### Step 6: Review and Revise
Before finalizing your sankey chart, review it to ensure it is clear and effectively communicates the intended message. Adjust any elements as necessary to improve readability and visual impact.
## Interpreting Sankey Charts
### Analyze the Flows
Begin by observing the width of the lines, which indicates the magnitude of the flow between different categories. Larger lines signify greater quantities.
### Understand the Distribution
Pay attention to the source and sink nodes to discern where the largest inputs and outputs occur. This can help in identifying both the largest contributions and the greatest impacts.
### Look for Patterns and Trends
Sankey charts can reveal seasonal patterns, cyclical processes, or trends in the data, such as increasing or decreasing flows over time.
### Compare Groups
If your sankey chart includes multiple datasets (e.g., different years or regions), compare the flows across categories to identify significant changes or similarities.
### Spot Hotspots
Identify nodes with high inflow or outflow. These can represent critical points in the system, such as high production or consumption areas.
## Conclusion
Sankey charts are invaluable for visualizing complex systems, making invisible flows and distributions tangible and understandable. By following the steps outlined for creating and interpreting these charts, you can unlock deeper insights into your data, aiding in informed decision-making and effective communication of complex information. Whether you’re analyzing industrial processes, economic transactions, environmental flows, or anything in between, sankey charts provide a clear, visual approach to understanding and explaining complex data flows.
