Typical Usage Of Color in Data Visualization

Given below are the possible methods to use Colors in Data Visualization

Categorical: Each color represents a different category
Sequential : Color is ordered from low to high
Diverging : Sequential color presented in opposite directions from a mid-point
Highlight : Color draws attention to a particular element or elements
Alarm : Color alerts/ warns the reader or end-user of some anomaly

We will be making use of a Map View to show the different usages of color.

Color as Categorical

Assume we have a Map with the below mentioned configuration
State in Detail of Marks card
Region in Color of Marks card

This results in each Region coded by different colors
Blue : Central Region
Orange : East Region
Red : South Region
Green : West Region

Color as Sequential

Assume we have a Map with the below mentioned configuration
State in Detail of Marks card
Sales in Color of Marks card

This results in different shades of the same color to reflect the Sales across the States
Darker blue : Higher sales
Lighter blue : Lower sales

This can be confirmed with the Sales Color legend that shows the two extreme values. Sequential color works when we want to show low to high values using a continuous scale.

Color as Diverging

We can use a diverging color palette when we want to show values that are above and below a mid-point.

Assume we have a Map with the below mentioned configuration
State in Detail of Marks card
Profit in Color of Marks card with “Orange-Blue Diverging” color palette

Blue colored states have higher Profits than the average profit
Orange colored states have lower Profits than the average profit
This can be confirmed with the Profit Color legend and note that the mid-point does not have to point to a zero value.

Color as Highlight

Highlight colors are a special case of Categorical color when we want to instantly draw attention to something that we want people to notice.

NOTE: The state segregation in the above viz was achieved by creating groups in Tableau

The above map shows the State with lesser profits highlighted in blue color. We might need to do this as we believe that might be something about these states that will be of interest to the audience.

Color as Alert

Alert colors too are a special case of Categorical color when we want to instantly draw attention to something that we want people to notice.

NOTE: The state segregation in the above viz was achieved by creating groups in Tableau

The above map shows the least profitable state i.e., Texas is highlighted in Red color

Points to be taken care when using color for altering

But we need to be careful when making use of colors especially red for alerting purpose.

In western culture we normally equate Green with something positive or good and Red with something negative or bad

Stock Market: Green is up; Red is down

Traffic lights: Green means go; Red means stop

But this is not universal as in many Asian nations the associations with red and green are sometimes reveresed.
Sometimes organizations that have red logos tend to use red to mean something good.

Putting it all together

References:

Chapter 3 “How and when to use color” from the book “The Big Picture” by Steve Wexler — Data Revelations