Conceptual colors, negative proportions, mysterious axes, and all that

Reader Jordan G. found a different-looking chart on visualizing.org, of which I excerpted the following:

This part comes from the bottom right corner of an entire page of charts (link). The title of the entire project "Gaps in the U.S. Healthcare System" may give some hints as to what the designer was intending to portray. Looking at this part by itself, the reader is missing some information:

• What do the pink, orange, dark pink colors mean?
• What's plotted on the vertical scale that are in percentages?
• The horizontal axis may have something to do with distance/location. It's divided into three sections. Is it a continuous scale (say, kilometres or miles) or is it categorical scale (large, medium noncore)?

The first question is answered by the legend of the post, situated on the far left. Simply by printing the labels for racial groups on this chart, the designer would have saved readers the effort to look for this information.

The second question is not addressed anywhere on the chart but most likely, the percentages represent proportions of adults over 50 years old who ever received the three types of -scopies. The mirrored nature of the vertical axis is odd. As much of the chart is above the zero-proportion line as exists below the line. What does negative proportions mean?

Because I couldn't figure out the answer to the third question, I can't interpret this chart at all. I see that the proportion of adults fluctuates from left to right for every racial group. But with what is the proportion varying? It also appears as if Asians only live in urban areas.

***

Jordan asks a question about color choice here that is worth discussing.

In this chart, the author chooses to use a color coding system to represent race (pink squares = African Americans).  I have seen other charts use “actual” colors to represent race (white = Caucasian, black = African American).  I could see some audiences taking offense at these different color representations, especially where the color chosen has been used pejoratively in the past (like “red” for American Indian, “yellow” for Asian).  What would you consider an effective and appropriate way to encode different races on visualizations?

 

Comments

[dan l]

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What would you consider an effective and appropriate way to encode different races on visualizations?
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I would go to color brewer and get a couple of random colors. There's simply nothing good that comes out of trying to encode the colors with any perceived 'realism'.

[Antonio]

I think that we have to change olympic flag. The five colors are not politically correct. It is better to use numbers. But not 13 and 17 which are unlucky (in my country). And not six because triple six is the satanic number. And not odd, because "odd" seems a bit strange. And not large because... No, just a step back. Maybe it is better to use letters. Not only from M to Z, since letters from A to F can be interpreted as votes, and J is Joke. Just a moment. A mathematician can argue that R is better than Q and Z, because there are more reals than rationals and integers... Please discard them. Uhm... ok, I am. Use hieroglyphics. And kill every Egyptologist. Yes, this is a great solution.