Flow, process and networks
Alluvial diagram
Shows how group quantities are distributed between categories at successive stages.
- Diagram
- Flow
- Composition
What it answers
How do group memberships change across stages?
- Shape
- Category blocks linked across stages
- What it shows
- Group continuity and redistribution.
Example
The question
How did customers move between plans over three years?
Customers by plan, 2023 to 2025 (alluvial diagram, hundreds)
Illustrative data. It belongs to no company.
When to use it
Use it when
Categorical transitions where complete paths matter.
Avoid it when
When only unrelated stage totals are known.
How to read it
Follow bands through ordered category axes and compare band widths.
Note
Conventions overlap with Sankey diagrams.
The data you need
- Layout
- Wide path-count table
- Fields
- Stage1,Stage2...: category text; Count: nonnegative number
- One row is
- One category path across stages with its frequency. What is the grain?
- Rules
- Declare stage order and aggregate identical paths. Keep counts nonnegative.
- Optional
- Raw alternative: EntityID,Stage,Category. Edge-only data may lose complete path identity.
- Preparation
- Validate the input grain and missing values. Declare stage order and aggregate identical paths. Keep counts nonnegative.
- Units
- Relationships and positions have no numeric unit by default. Label any counts, durations, probabilities or weights separately.
Worked example
Paths A-B-D30 and A-C-D20 start with 50 in A. At stage 2,60% pass throughB and 40% throughC.
| Stage1 | Stage2 | Stage3 | Count |
|---|---|---|---|
| A | B | D | 30 |
| A | C | D | 20 |