color-encoding-for-data

• SKILL.mdcore · 4,147 bytes

# Color Encoding for Data

## When to use
Use this on any chart once it is built and labeled. Color is the most misused element of a chart. Done well, it makes the message jump out before the reader reads a word. Done badly, it turns a chart into a rainbow that hides the point.

## What it does
It returns a color plan: the base palette, which element gets the accent, the palette type for the data (categorical, sequential, or diverging), and an accessibility check. The plan ties every color to a reason.

## Method
Step 1. Start from one color, add color only to mean something.
The default is a single muted color for all marks. Add a second color only to encode a real distinction: the focus category, increases versus decreases, above versus below target. Color with no meaning is decoration and should be removed.

Step 2. Use preattentive contrast to direct attention.
The eye locks onto the one element that differs in color before conscious reading begins. Exploit this: gray every mark except the one the message names, and give that one the accent color. A single accent bar in a field of gray is read faster than any label.