1/21/2019
Bar Hopping: Theme and Variations on a Bar Chart
If you've spent time visualizing data then you have likely heard the phrase, "bar charts are boring". We know from research that bar charts can be very effective for encoding data for precise quantitative comparisons, but often times clients, customers or stakeholders ask for "something different". Others have argued that it's the data that is boring, not the chart. While I agree with that premise, I decided to explore some variations on the design of a simple bar chart to demonstrate that all bar chart design does not have to look the same.
A Simple Bar Chart
Here is a simple bar chart showing the percent of sales across four regions. However, many of these designs below can be done with absolute values rather than a percent of whole.
Rounded Edges
This variation uses rounded edges. Be careful when doing this. If adding a dot to the end of the bar, the bar will extend past the actual value, which is the center of the dot. This can be adjusted, but the size of the dot is also a factor. In this example, I chose a smaller dot and thinner bar line so that the dot would not go too far past the end of the bar.
Outline Bars
Sometimes the color of the bars can be overwhelming. In this variation I remove the color on the bars and simply outline the bars.
This is the same technique that I used in the Web Analytics dashboard in Chapter 13 of the Big Book of Dashboards.
Notice the bars in the histogram of pageviews by weekday. When the bars are filled in, the histogram draws the attention of the eyes more than the other elements of the dashboard. By using an outline of the bars, it blends into the dashboard design more evenly. This is done simply by outlining the bar instead of filling it with color.
Progress Bar and Thin Progress Bar
If showing a percent of a total, then a progress bar can be an excellent way to show the information. Below are two examples, a progress bar and a thin progress bar.
Lollipop Chart
Using a thin line and a dot or cirle creates a lollipop chart. Some in data visualization community have expressed concerns with lollipop charts because the the dot extends past the end of the line. Therefore, if using a lollipop chart, I would recommend keeping the dots smaller so that it is more accurate.
Thin Bar with Line End
As mentioned above, one issue that comes up with the use of lollipop charts is that the dot on the end of the lollipop can extend the data past the end of the bar. This solution solves for that problem, by capping the end of the bar with a line. This will provide the same precision as a bar chart, but reduces the ink, even less than the outline bars.
Progress Bar with Thin Line
Here are two other variation of the progress bar, one with a thin line across the middle and the other with a thin line across the bottom. In both cases, the bar shows the percent of whole and the line represents 100%.
Unit Chart
A unit chart is very simple, it's a bar chart that has been divided into units. This is a very clean look and easily understood.
Cleveland Dot Plot
This next variation is not a bar chart, but it serves the same purpose. William Cleveland referred to it as a dot plot. Each dot plots the value and the dotted line shows the whole range of 100%.
Unit Chart Progress Bar
Combining the progress bar and unit chart gives us the last variation. The percent is shown across the units, in this case in 10% increments, but the entire range up to 100% is also shown.
Below is a Tableau Public viz showing all of these variations. There is a parameter to change the color scheme. Feel free to download this workbook to see how these were built.
