Understanding Sankey Charts: A Comprehensive Guide

Understanding Sankey Charts: A Comprehensive Guide

Sankey charts, also known as Sankey diagrams, are a type of flow diagram used to visualize the distribution and flow of resources, energy, or any measurable entity across different processes or stages. Named after Irish engineer Matthew Henry Phineas Riall Sankey, these charts are especially effective in showcasing the efficiency or inefficiency of a system by visualizing the proportions of inputs, outputs, and losses at various stages.

What is a Sankey Chart?

At its core, a Sankey chart is a flow diagram where the width of the arrows is proportional to the flow quantity. This makes it different from other types of flow diagrams, as the thickness of the lines is not uniform but varies depending on the magnitude of the data it represents. It gives an immediate visual impression of the relative size of each flow in the system.

For instance, in a system of energy flow, the diagram can show how much energy enters the system, how it gets used in different processes, and how much is lost as waste. The thicker the line, the larger the flow, making it easy to identify where resources are being consumed or wasted.

Components of a Sankey Chart

A Sankey chart consists of the following key components:

1. Nodes: These represent the different entities or stages in the system. For example, in an energy flow diagram, nodes might represent processes like electricity generation, distribution, and consumption.
2. Flows (Links): The flows or links are represented by arrows or bands connecting the nodes. Their thickness corresponds to the quantity being transferred from one stage to another.
3. Flow Direction: The arrows show the direction in which the resources or data are moving. This helps in tracing the journey of an entity through different processes.

Applications of Sankey Charts

Sankey diagrams are used in a wide range of fields due to their effectiveness in visualizing complex systems. Some common applications include:

1. Energy Flow Analysis: One of the most common uses of Sankey charts is in energy flow analysis, where they map the journey of energy from generation to consumption, highlighting inefficiencies and energy losses along the way.
2. Material Flow Analysis: Sankey charts can help in analyzing how materials move through production processes, identifying stages where there are bottlenecks, waste, or inefficiencies.
3. Supply Chain Management: Companies use Sankey diagrams to visualize supply chain flows, from suppliers to the final consumers, helping in optimizing the movement of goods.
4. Financial Analysis: Financial analysts can use Sankey charts to display cash flow within an organization, identifying where the majority of funds are allocated and where they are leaking.
5. Website Traffic Analysis: Sankey diagrams are increasingly being used in digital analytics to show how website visitors flow through various pages, giving insights into user behavior and potential areas for optimization.

Benefits of Using Sankey Charts

1. Clear Visual Representation: One of the biggest advantages of Sankey charts is their ability to provide a clear visual representation of complex processes. Users can quickly identify the largest flows, losses, and inefficiencies at a glance.
2. Easy Comparison of Data: By varying the thickness of the arrows, Sankey charts make it easy to compare the magnitude of different flows within a system. This is particularly useful for spotting inefficiencies or areas for improvement.
3. Engaging and Informative: These charts are visually engaging, making them more likely to be understood and appreciated by stakeholders, especially when used in presentations or reports.
4. Ideal for Complex Data: Sankey charts excel in cases where there are multiple inputs and outputs, making them an ideal choice for systems that involve many interconnected parts or complex workflows.

Creating a Sankey Chart

Creating a Sankey chart can be done using a variety of tools, ranging from specialized software to popular spreadsheet programs like Microsoft Excel or Google Sheets. Here’s a basic process to create a Sankey chart:

1. Data Preparation: First, gather the data representing the flow you want to visualize. This could be energy data, material usage, or any other measurable quantity.
2. Software Selection: Choose a tool that supports Sankey diagrams. Some popular tools include:

• Google Charts API (web-based)
• Microsoft Excel (with add-ons or custom templates)
• Tableau (for more advanced visualization)
• Power BI (widely used in business analytics)

1. Input Data: Input the nodes and the quantities of the flows between them. Make sure to indicate both the starting and ending points of each flow, as well as its value.
2. Adjust Visual Elements: Customize the appearance of the chart by adjusting the colors, labels, and thickness of the flows to make the diagram clear and intuitive.
3. Interpret and Share: Once the chart is created, it’s time to interpret the data. Identify areas where there are inefficiencies, losses, or opportunities for optimization.

Conclusion

Sankey charts are a powerful tool for visualizing data flow, making it easy to see the relative proportions of different components in a system. Whether you’re analyzing energy use, material flows, supply chains, or website traffic, Sankey diagrams can simplify complex data and help you communicate insights more effectively. By allowing for easy comparison and identification of key issues, these charts are indispensable in industries ranging from engineering to finance.

In an age where data visualization is increasingly important, Sankey charts offer a unique and visually appealing way to understand the dynamics of complex systems.