# Data Visualization - how to display error of a color scale?

I've been turning this around in my head and I think the answer is to ultimately tabulate the data, but it's an interesting question so I'll still post it.

I have three sets of data of equal length. Two of these sets, call them X and Y, are plotted against each other on a scatter plot. The third set, C, is overlaid on the scatter plot as a color map. All three of these sets have a standard deviation associated with each point.

It's easy enough to denote the standard deviation as error bars on the scatter plot points. But how does one typically denote the standard deviations on the color map?

• Don't use colors! They are so poor at conveying quantitative values that it is hopeless to try to modify them to reflect the standard deviations. There are plenty of better choices, ranging from using better symbolism (e.g., vary the size of the point symbols instead of their color) to a different chart (e.g., use a scatterplot matrix).
– whuber
Jul 22, 2020 at 14:25
• @whuber also good advice! Typically I discourage using color in graphs because a) nobody does it right and b) it's hard to discriminate values. Fortunately, the use of color, while tied to physical quantities, it meant to be a semi-qualitative way to guide the reader to observe a general trend, not convey any particular values. I thought about changing the size of the points, but the data is already too clustered as it is, and a lot of the meaning would be even more obscured. Jul 23, 2020 at 12:24
• There are alternatives, such as transparency, hexbin plots, sunflower plots, etc. But it sounds like you might be stuck with the color requirement, which narrows your options.
– whuber
Jul 23, 2020 at 14:08
• I looked those plots up, and I think some of the older brains in my field would explode if they saw them. The hexbin plot is intriguing, though...I may try that and see what my coauthors think. Jul 23, 2020 at 17:38