It’s quite astonishing how even when I get out of my office and resolve not think about my work for a while, I stumble upon something that makes me think about… my work. (Oh, the sweet and eternally elusive fantasy of escape.)
Take this morning. Bret and I were on a walk in the woods with our pups when we happened upon an old cemetery and this antique gravestone:
Finding an old cemetery in the woods is interesting, but it was the relief on the gravestone of a finger pointing toward the heavens that really caught my attention. Was this an instruction for those who would be helping the deceased (John Young) into his next life, or simply a message left for all of us earthbound souls about where he had gone — a reassurance of sorts? No matter: it amused me immensely and made me think about the directional icons we use in data visualizations.
Dead people, data viz icons… don’t even try to imagine living in my head.
We sometimes use icons in our data visualizations to grab a viewer’s attention and direct it toward something important or that requires action. Icons alert the viewer to “see this,” or say in clear, firm tones, “this is urgent; do something!”
The icon shapes we use most often are up- and down-facing carets to show that one measure is greater or less then another (for example, actual performance compared to target|budget), or — in the case of a performance over time — the way something is trending.
Depending upon what result or direction is desired, color may be applied to the icons: red for an undesirable value, say, and green for a desirable one. A word of caution here: you have to think through the use of these types of icons very carefully. If different measures with different directionality of good v. bad are displayed together, the mix may cause confusion for all viewers.
And yes, I know that we discourage the use of the colors red and green together, because about 8% of the world’s population is red|green color-blind; but if it makes sense to use this type of icon for those who are not, go ahead. The 8% can still perceive the directionality conveyed by the carets.
Keep in mind, of course, the above-noted problem of mixing metrics with different performance goals. (If this stuff were simple, everyone would do it right without our help!)
If we don’t want or need to show directionality or greater than|less than specifically, we simply use points and different saturations of a single color (usually red) to signal degrees of difference between one measure and another — to tell the viewer where to look first, beginning with the deepest saturation, then moving to the next and the next.
And yes, dear reader, it’s true that red|green color-blind people can’t see the red color on these icons, but they can perceive a shape that signals “look here.” They can see saturations of color from deepest (most urgent) to lightest (relatively less urgent) that display something like this:
We do NOT, however, use green and red points together for several reasons. First (and yes, I know this may be provocative in some circles, which makes it even more fun for me to write about), the purpose of a true management dashboard isn’t to pat anyone on the back with lots of green points that signal “good job!”; rather, we need to keep our displays uncluttered and use this type of icon only to call out and highlight areas of concern (you know: the type of poor performance that might sink the ship or land your organization on the front page of the local newspaper — and not in a good way).
Another example of how we have used icons to communicate and draw viewers’ attention to a specific performance in comparison to percentiles is shown in the following display of State Medicaid agency results on Behavioral Health Care metrics. Here, we’ve used both shape and color to convey information.
A blue checkmark indicates performance at or above the 75th percentile. The purple minus sign in a circle for performance falling between the 25th and 75th percentile is somewhat neutral. The “Hey! Look here: this needs immediate attention” 25th-percentile-or-below results icon is a red x.
There are also occasions when you should not use any color conveying good or bad performance on an icon. For example, you simply want to communicate that a value has increased or decreased. The viewer’s knowledge of the metric is required to determine whether that change is a good or a bad thing.
The following illustrates what I mean. The arrow icons show only that a hospital payor type has increased or decreased from one year to the next. Given the complexity of hospital contracting and reimbursement, we don’t have enough information to decide what is good or bad for this hospital, so we don’t use a signifying color. We leave that judgment to the contracts and reimbursement experts who work there.
After seeing John Young’s gravestone, I got to wondering about some of the other icons that exist in our day to day world. Is the up arrow in the image below pointing to the heavens, or merely showing me the way to my meeting on the 8th floor? Let’s hope it’s the latter!
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