In the PM (it’s actually called “software methodology, but I assign a project, so students can experiment with methodologies) class I teach at TGI, I ask the students to create (and then use) a project dashboard, so they have a quantitative way to see their progress (or lack thereof). The students presented their dashboards last week.
One of the teams adapted a traffic light, with red, yellow, green, and blue (for done). The student who presented the traffic light to the class, said something like this, “We added blue, to denote done. I think it’s right there.” I said, “Can’t you see it?” He said, “No, I’m color blind.”
I did about 5 minutes of online “research” and realized that about 5-7% of men can’t distinguish red from green. Some fewer can’t distinguish between blue and green (the problem my student had).
So, if you’re going to use a traffic light (which I don’t like. See Sunny Skies or Storms? for an alternative to the traffic light), make sure your viewers can see it.