The Flow of Truth: Unfolding the Secrets of Sankey Charts
Sankey charts, a visual representation that captures the complexity of data flows, have been used since the late 19th century for various applications ranging from energy flow to material balances. They offer a clear, concise way to visualize how information or energy moves through a system. In this article, we’ll explore the creation and applications of Sankey charts, unpacking their significance and practical uses in data analysis and design.
Understanding Sankey Charts
Basics of Sankey Charts
Sankey charts are named after Irish engineer Matthew Sankey, who used them in the 1880s to visualize the thermal energy produced in steam engines.
Key Characteristics
- Flow Representation: Sankey charts use arrows to represent the flow of things (energy, water, materials, etc.) between different components of a system.
- Direction of Flow: The arrows typically flow from left to right, with the width of the arrows representing the amount of flow – a thicker arrow indicates a higher flow rate.
- Energy Law: There is a natural rule to Sankey charts that ensures an energy or material cannot flow into an area that doesn’t have a path out, making the charts inherently logical.
How They Work
Sankey diagrams work by splitting each arrow into segments that represent different parts of the flow process. Each segment has a consistent width to show the flow rate for that segment.
Steps for Creating a Sankey Chart
Gathering Data
The first step in creating a Sankey chart is to gather your data. Whether you’re dealing with physical flows or more abstract information, you need a thorough understanding of how the flow works.
Establishing Nodes
Nodes are the points that signify where the flow starts and ends. They typically represent processes, systems, or components of a workflow.
Determining Links
After identifying the nodes, you need to determine the flow paths—these are the connections between nodes.
Mapping the Flow Widths
Flow width is crucial for showing relative magnitudes. The width of the arrows should be directly proportional to the magnitude of the flows they represent.
Connecting Nodes
The final step in creating a Sankey chart is visually connecting the nodes using arrows or wide lines that start at the ‘input’ and end at the ‘output’.
Utilizing Software
Today, there are numerous software tools available for creating Sankey diagrams, from the original software created by Sankey himself to modern graphing tools like Microsoft Excel, specialized Sankey diagram software, and web-based platforms.
Applications of Sankey Charts
Energy Flow Analysis
Sankey charts are invaluable for visualizing energy flows within a system, such as in power plants or homes. They can illustrate how much energy is lost at each stage and where improvements can be made to increase efficiency.
Environmental Management
Sankey charts can represent the flow of materials and energy in industrial systems, enabling businesses to understand their environmental footprint and identify areas for waste reduction or sustainability improvements.
Logistic and Supply Chain
Sankey charts are also useful for visualizing supply chains and logistics networks, showing how resources move from suppliers to consumers.
Economic Analysis
For economists, Sankey charts visualize money flows and economic relationships between different sectors, highlighting the efficiency and impact of various economic activities.
Data Analysis
Within data analytics, Sankey charts are used to visualize the movement of data and information within a system, providing insights into how information flows and where bottlenecks may occur.
Conclusion
Sankey charts are more than just a tool for visualizing data; they are a window into the flow of information and energy within or between systems. By presenting data in a compact yet informative format, Sankey charts continue to be a vital resource for a wide range of applications across various fields. As data collection and analysis tools become more sophisticated, the relevance and utility of Sankey charts are not diminish, but instead, their potential roles expand to new areas, making them a true ‘flow of truth’ for complex systems.
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