What is Treemap?
A treemap is a compact, visual way to show hierarchical or part‑to‑whole data using nested rectangles whose sizes represent numeric values and whose colors can encode categories or metrics. It's useful for seeing which parts of a dataset are biggest or smallest at a glance.
A treemap displays data as a set of nested rectangles. Each rectangle represents a category or subcategory; the area of a rectangle is proportional to a numeric value (for example, number of responses), and color can be used to show a second measure (for example, average satisfaction). Treemaps are space‑efficient and good for showing relative sizes and hierarchical structure — for example, responses grouped by language, then by neighbourhood or question topic. They are best for high‑level overviews rather than precise comparisons.
Usage example
On Hearo, a treemap could show survey responses by language: each language is a large rectangle sized by total responses, and inside each language rectangles for different schools or districts. Colors might indicate average satisfaction so you can spot both where most responses come from and where scores differ.
Practical application
Treemaps help organisations quickly identify which groups are most or least represented and where to focus engagement or translation effort. For example, you can spot a large language group with low response rates from a particular neighbourhood, or find small but important communities whose voices risk being overlooked. Treemaps are particularly useful on dashboards because they present hierarchical breakdowns without multiple separate charts, making it easier to prioritise outreach and interpret multilingual survey results at a glance. Keep in mind they’re best for spotting patterns and outliers rather than exact value comparisons.
FAQ
How do I read a treemap?
Read rectangle area as quantity (bigger = more). Nested rectangles show hierarchy (parent categories contain child categories). Color usually represents a second metric (for example, sentiment or average score).
When should I use a treemap instead of a bar chart or pie chart?
Use a treemap when you need to show hierarchical breakdowns or many categories in a compact space. Use bar charts when you need precise comparisons between a small number of categories, and pie charts only for simple part‑to‑whole views with few slices.
Can a treemap show percentages or multiple metrics?
Yes. Area can represent counts or percentages of the total, while color or shading can encode a second metric (for example, average satisfaction, completion rate, or change over time).
What are the limitations of treemaps?
Small rectangles can be hard to read or compare precisely, and differences in area are less intuitive than length comparisons. Treemaps are best for getting an overview and spotting big differences or outliers rather than exact comparisons.