What is a common use case for a Sankey Diagram?

A Sankey Diagram is primarily designed to visualize the flow of data or the movement of quantities between two or more entities or stages. This type of diagram uses arrows whose widths are proportional to the flow quantity, making it particularly effective for showing how data, resources, energy, or costs are distributed and transferred across different processes or categories.

In contrast, while survey results, customer satisfaction surveys, and comparisons of categorical data are important visualizations in data analysis, they are not the primary focus of a Sankey Diagram. Survey results and customer satisfaction are better served by bar charts or pie charts as they present categorical data effectively. Similarly, comparing categorical data typically relies on methods like clustered bar charts, histograms, or box plots, which are more straightforward and suited for directly contrasting discrete categories rather than illustrating the flow between them. Thus, the usage of a Sankey Diagram for tracking data movement or flow is its most fitting application.