Myths about Red-Green Deficiency in Visualizations

Disclaimer: I am not an “Ophthalmologist”, so don’t cite me here and if you actually have a red-green blindness and/or disagree on the following article please ping me via LinkedIn. It is not as simple as it seems. 😊

Color is a crucial element in data visualization and communication, significantly impacting how effectively information is conveyed. When discussing International Business Communication Standards (IBCS), I hear very often an argument against the use of red and green. The ongoing debate about the use of red and green, primarily due to concerns related to color deficiency needs to be cleared up. There are definitely incomplete arguments floating around. In this article, we’ll explore the misconceptions surrounding IBCS Red-Green Deficiency and how a more nuanced perspective can lead to a better communication.

Understanding Color Deficiency

Before delving into the myths, it’s important to grasp the concept of color deficiency and its prevalence. Approximately 8% of men and 0.5% of women of Northern European descent experience red-green color deficiency, also known as color deficiency, not blindness. Nevertheless, it’s vital to remember that not all cases are the same, and there’s a spectrum of color deficiency types, and varying degrees of severity. If I am not mistaken less than 1% of all are completely blind for red and green. And even less with 0.00001% being impacted by Rod Monochromacy, which is actually completely color blind.¹

The 2 Myths

1. Myth: Sacrificing Pattern Recognition for a Fraction of your Target Audience
   • Since we know now the difference between being color blind and having a deficiency do we really sacrifice our reports for a minority and are there not better options?
   • Red and green are universally recognized as symbols for negative and positive, respectively—a concept deeply ingrained in our psyche. Eliminating these colors could lead to immediate loss of this intuitive “color coding”. There are more effective ways to enhance accessibility. Modern tools are capable of adapting. For instance, while red and green might be the default, an automatic switch to alternative colors can be implemented when necessary.
   • It’s important to note that even the 0.00001% can distinguish red and green if you help them. If you use red and green consistently than they should be able to differentiate them based on saturation. By consistently using highly saturated colors for red and less saturated for green, it could be possible to differentiate the colors based on saturation. However keeping in mind that if you choose a low saturation for green you will make it especially difficult for people with green-deficiency. An example of this approach is illustrated at the bottom of this article.
2. Myth: The Challenge of Judging a KPI as Positive or Negative in Multi-Audience Reports
   • Another common fallacy is the assumption that in a report designed for multiple audiences, the judgment of a Key Performance Indicator (KPI) as positive or negative becomes ambiguous and difficult. However, this misconception arises from the belief that a report can be effective without a well-defined target audience.
   • In reality, the key to addressing this challenge is recognizing that a report should always be tailored to a specific target group. A report designed to cater to different audiences without a well-defined focus is destined to be subpar. By specifying the target audience, the report’s content and presentation can be tailored to meet the unique needs and expectations of that group.
   • And if you ever happen to really don’t know if a deviation has a positive or negative impact, than use a neutral color. IBCS never told us to not use any colors, just use it for a purpose and be consistent in what you are doing to achieve pattern recognition for better decision making.
   • Also, in the unlikely case you actually had to design a report for a multi-audience group than also go for a neutral color, if those different groups also perceive it differently. Like for example if you want to highlight increased “personal costs” within a PnL and your audience is work council + management of the company, than okay use a neutral color. But those examples are definitely the exceptions and not the norm.

Practical Recommendations:

1. Don’t pick green and red colors with both having a low saturation
2. Consult Those Affected: When creating reports or data visualizations, consider seeking input from individuals with color deficiency. Their insights can prove invaluable in selecting appropriate color schemes and ensuring that the content remains accessible and inclusive.
3. Print your Reports to test in Greyscale: To guarantee that your content remains legible even when viewed in black and white or grayscale, regularly assess your designs in these formats. Or alternatively even better go to a website like the following and test your dashboards there: https://pilestone.com/pages/color-blindness-simulator-1
4. Use a neutral color if there is really no good or bad, like a blue.
5. Relative deviation pins are hardest to grasp, always combine them with absolut bars in order to have more ink and bigger bars to give to your audience.

Conclusion

In conclusion, it is not as simple as it might seem. While concerns about color deficiency are valid, they should not lead to the blanket avoidance of red and green. Instead, a more nuanced approach that considers the specific context, audience, and accessibility needs should guide our choices. By consulting those affected, testing in greyscale, choosing contrasting shades of red and green, and resorting to neutral colors when necessary, we can strike a balance between effective communication and inclusivity in data visualization practices.

Concrete tip: Those are the colors I personally use:

• Microsoft Office Standard Red: 255, 0, 0 or #FF0000
• Microsoft Office Standard Light Green: 146, 208, 80 or #92D050

But please keep in mind that the dark green might work as well. Especially for people who are green-weak this is most likely the preferred color. Also even though it might be possible and worth considering to identify a color based on saturation, for people with deficiency high-saturation on high-saturation can be a good option too.

1. https://www.colour-blindness.com/general/prevalence/ ↩︎