Which shades of red and green are safe to use together?
So I decided to do a little spare-time research and document it (so I don't forget).
What about the 80/20 rule?
I don't think that rule should be taken literally. I totally get that about 8-10% of people (mainly men) worldwide are color deficient and it does beg the question, why go through this consideration for just 8%? I can think of three ways to respond to this:
- If you know your audience isn't color deficient, then no need to concern yourself. Though maybe that super awesome viz you did on pay equity or wildfires or [insert super important topic here] might go viral or get picked as a viz of the day (and then 1,000s more may now be in your audience).
- You might not know who is in your audience. What if you chose reds and greens that are hard to distinguish in your 'Should we begin a military action?' viz you are presenting to the president? If you were presenting to Bill Clinton, that might have been an issue. Can you imagine the president not being able to read your viz? Not a career highlight.
- Consider the converse. In the 80/20 rule, 20% of readers may miss your message. Yikes, that sounds like a lot! So 8% might miss the message, so what? Eight is a lot better than 20, but looking at it from various perspectives, exceptions that are over 5% (and even 1% in some industries) might be too high. But I hear someone asking, “What about the other types of color deficiencies besides the red/green types, Em?” Those are 1% or less and so I put those in the 3rd standard deviation bucket. My position (until my learning evolves my position) is that it seems reasonable to capture two standard deviations.
Does this mean you have to be a Grinch at Christmas?
I put an image of Chris's viz through VizCheck and here's what it looks like for the three types of color deficiencies.
Use a high contrast red and green color palette to ensure everyone can #seeallthedata.