Sankey Diagram

A Sankey diagram is a chart that shows flow with bands whose width is proportional to the volume moving from one node to the next.

The Sankey diagram is the default visual language of path analysis because it shows volume and branching at once: each column is a step, each node a page or event, and the band widths say how traffic splits. The biggest reading trap is mistaking band width for success; width is only volume, and the heaviest branch can be a confusion loop or an exit route. The second trap is node explosion: each extra step multiplies the branches and the chart collapses into a chaos of thin bands, so for readability you must keep the step count low and group similar pages. The key point is that a Sankey is a display method, not a metric; the analytical value comes from how the nodes are defined and the direction of flow, and a beautiful Sankey over ill-defined data only makes the error prettier.