# Data visualization for showing a person's decile

Consider a service where you can inquiry someone's SSN and you will be shown his personal information and his income decile among the population of his country is one of those information. Right now a bullet graph is being used to show the decile because of its space efficiency (picture below)

As you can see the middle bar isn't as descriptive as I thought it'd be and when someone is part of 10th decile the full length of bar isn't just showing it well, and seems that the indicator bar is part of the graph itself.

I need suggestions on improving or replacing the bullet graph, any helps are appreciated.

• I'm struggling with some of the terminology you're using: Can you explain "SSN"? – Andrew Martin Sep 27 '17 at 8:29
• @AndrewMartin Social Security Number (It's actually called national number in my case, a unique number assigned by government to each person) – Nima Hakimi Sep 27 '17 at 9:46

Looking at the example, even having read the description, it took me some time to work out what the graph was showing, and I think the problem is this:

If you see a diagram only once, and it is only showing one piece of information, it is very hard to distinguish between the structure of the diagram and the actual content. For instance, if I see this diagram six times:

then it's clear how to read each individual diagram. But if I see it only once, I don't know if I'm looking at the green divisions, the thick bar, the thin bar, etc.; and the problem is even worse if this one example happens to show the minimum or maximum value.

If your users are likely to see the diagram only once, then you are introducing them to a new visual language and trying to communicate to them using that language, at the same time. You could try using familiar idioms to help explain the graphic:

Or it might be better to simply use text (e.g. "90% earn less")...

• What about space concerns? "bullet graph is being used to show the decile because of its space efficiency" – Ada Oct 8 '17 at 9:31
• I think the examples I suggested would work at a smaller size. But there’s a trade-off between a diagram being simple and it being easy to understand. That’s why I mentioned using text as a serious alternative— people have spent a lot of time optimising written Persian to graphically convey information in a small space. – bobtato Oct 10 '17 at 17:14

I think @Ada's answer is an improvement on the original. However, I'm not sure that a bullet graph is a great approach.

Another approach would be a 10-bar histogram with the bar representing the current percentile highlighted, but with limited vertical space here (and if you need to show multiple rows) that may not work well. Something like this image.

A way to simplify the bullet graph would be to convert it to a simple bar / progress bar with the percentile as a label. Something similar to this image.

I think either of these options would be clearer at first glance, and unless you need the additional information of the bullet graph (performance vs. benchmark, qualitative ranges), it would probably be better to use a simpler visual representation.

My solution is to put an indicator in the graph. Also if it is pointed in the middle of the decile section, then it will never gets into a confusing position of starting or ending point.