CHARTS / PRACTICAL GUIDE
Sankey diagram: examples and when to use it
A Sankey diagram connects nodes with bands whose widths encode quantities. It shows how a total splits, merges or moves through a system.
When to use it
Use it for energy balances, material pathways or transfers between stages. It works best when the reader needs to follow the structure of a flow.
When to choose another view
Use a map when geographic locations are essential. Use a bar chart if the reader only needs an accurate ranking: band widths are harder to compare than aligned bars.
How to read it
Follow each band from its source to its target. Wider bands represent larger values. Check whether intermediate nodes have balanced incoming and outgoing quantities and whether losses are included.
Data format and example
One source, one target and a nonnegative numeric value per connection. Combine repeated connections only when they represent the same scope and unit.
| Source | Target | Value |
|---|---|---|
| Coal | Power | 90 |
| Gas | Power | 40 |
| Solar | Power | 30 |
| Power | Residential | 80 |
| Power | Industry | 80 |
Make it in Datamon
- Name the stages consistently and prepare one row per connection. Include units and the reporting period.
- Choose Sankey and map the source, target and value columns.
- Inspect repeated links, disconnected nodes and any cycles. Check balance at each intermediate stage.
- Limit labels to meaningful stages. Use a table alongside the diagram when exact values matter.
Common mistakes to check
- Do not mix quantities measured over different periods or in different units.
- A transfer is not automatically conserved: losses or additions need explicit treatment.
- Too many tiny flows obscure the main paths. Group them transparently and retain the detailed table.