Use a diverging color scale when the story depends on both extremes
For extreme-value emphasis in quantitative color-encoded charts, use a diverging color scale on data where both low and high ends matter to improve insight and address one-sided emphasis on only the highest values for readers scanning extremes.
- purpose:refine
- basis:heuristic
- task:extreme
- data:quantitative
- quality:insight
- lever:encoding
- communication:framing
- aesthetic:color:use
advice
Use color to highlight both tails
Use a diverging color scale when the story needs the lowest and highest values to stand out together. For example, replace a sequential light-to-dark map that mainly spotlights the highest values with a diverging map that also brings very low values into focus.
reason
Why diverging scales spotlight both ends
A sequential ramp naturally concentrates attention on its darkest end. A diverging ramp gives visual weight to both tails, so low values no longer disappear into a pale continuation of the same gradient.
Mechanism: Two opposing color directions make both extremes salient instead of giving the strongest emphasis to only one end.
Evidence: The article describes sequential versus diverging as an editorial choice: sequential scales support stories about the highest values, while diverging scales support stories about the lowest and highest values and bring low values into focus (https://www.datawrapper.de/blog/diverging-vs-sequential-color-scales">Muth, 2021).
context
Use when both extremes are part of the message
- User Goal: Emphasize both tails of a quantitative distribution.
- Task: Highlight extremes rather than only rank the top end.
- Data: Quantitative values spread across low and high ends.
- Chart Setting: A chart or map already using a quantitative color scale.
- Audience: Readers are scanning for where the extremes are, especially at the low end.
- Success Criterion: Both low and high values are visually noticeable.
exceptions
Do not use when only the high end matters
Break it when: The message is mainly about the highest values. Why: A sequential scale emphasizes that single end more directly.
costs
Costs of emphasizing both tails
Sacrifice: You lose some of the simple one-ended emphasis of a sequential ramp.
Risk: The low end may draw more attention than intended.
Mitigation: Use a sequential scale if the message is only about the high end.
mistakes
Common extreme-emphasis failure
Mistake: Keeping a sequential scale when the intended message is about both low and high extremes. Why it fails: The low end stays visually subdued.
check
Check whether both tails are visible
Failure Sign: Low values blend into the background while high values dominate.
Quick Check: Compare sequential and diverging previews; if only the diverging version makes the low end clearly visible and that matches the story, use it.
Stronger Test: Check whether both tails are easy to spot without reading exact numbers.
fix
Fix one-sided emphasis
- Replace the sequential ramp with a diverging ramp so each extreme gets its own side of the palette.
- Center the diverging scale on the middle point used in the story.
- Revert to a sequential scale if the message is only about the top end.