# Decoding Visual Complexity: Mastering the Art and Science of Sankey Diagrams
Sankey diagrams are visual tools that have become increasingly popular in the presentation of information, particularly when it comes to depicting flows and movements between different entities. Developed by Captain Matthew Henry Phineas Riall Sankey, a British engineer, in the 19th century for the graphical representation of energy expenditure in steam engines, sankey diagrams have evolved from their industrial roots to become a staple in a wide range of applications, from economics and business analysis to environmental studies.
## What Are Sankey Diagrams?
**Visual representation of flow** is the core aspect of sankey diagrams. This flow, much like that of water in a river, traces the quantity of energy, material, costs, or another specific variable along its path. Each ‘band’ or ‘link’ in a sankey diagram represents a quantity, with the width of the band indicating the magnitude of the flow. Consequently, the larger the width of the band, the more significant the flow represented.
## Key Features of Sankey Diagrams
### **Hierarchical flow representation**
Sankey diagrams excel in representing hierarchical or multilevel data, where flows are categorized not only by the source and destination but also by a third dimension such as types of flows or categories. This hierarchical structure is helpful in understanding complex networks with multiple layers.
### **Comparison of flows**
By displaying flows of resources, traffic, energy, or material, sankey diagrams enable direct comparisons between different paths. This comparative element is particularly useful when analyzing how much of a resource is spent on various processes or ends up in certain areas, often visually highlighting the disparities in quantity along the paths.
### **Storytelling through data**
The layout of sankey diagrams often guides the viewer’s eye through the data, revealing patterns, trends, and stories within the flow information. This makes it easier to communicate complex information effectively, engaging the audience and improving the understanding of intricate processes.
## How to Create Effective Sankey Diagrams
### **Data organization**
The first step in creating an effective sankey diagram is organizing the data in a suitable format. This typically involves listing sources, destinations, and the quantities being transferred between them. Data may need to be grouped or categorized according to specific criteria to ensure clarity and manage complexity.
### **Choosing the right layout**
Designing the layout of the sankey diagram is crucial. This involves deciding whether a one-layered, two-layered, or multi-layered diagram will be most effective for the data at hand. The layout should ensure that the flow is easily followed, and the diagram remains uncluttered.
### **Color and labeling**
Colors are often used to distinguish different types of flows or data categories. This helps in quickly identifying patterns and distinguishing between various components of the data. Labels are essential for explaining the quantities and categories in a way that is clear and accessible to the viewers.
### **Simplicity vs. information**
While aiming for simplicity is good practice, it’s equally important not to oversimplify to the point of losing crucial information. Balancing simplicity and detail is the key to effectively communicating complex data through sankey diagrams.
## Conclusion
Sankey diagrams, once a tool of industrial engineering, have become a versatile graphic representation method used across multiple sectors for explaining processes that involve flow. By effectively designing these diagrams, organizations and professionals can facilitate better understanding, decision-making, and communication of complex data. Whether tracking economic transactions, illustrating environmental impacts, or analyzing resource allocation, the unique ability of sankey diagrams to simplify complex visual information makes them an indispensable tool in the modern data-driven world.
