Today’s dashboard environments provide developers with a rich set of indicators and charts, ranging from bullet graphs to sparklines and bar charts to bubble graphs. Additionally, numerous formatting options such as splines and 3D displays are available, adding even more complexity. To the casual observer, chart types and options may appear to be largely interchangeable and are simply left to the discretion of the developer. But as the art and science of effective dashboard design has evolved, data visualization gurus have established some guidelines regarding which charts and indicators to use for various types of data and how to present those charts most effectively. This issue is receiving increasing media attention as dashboards migrate to the limited display “real estate” found on mobile devices, placing a premium on efficient dashboard based information delivery.
In this series of Dashboard Insight articles we’ll look at some popular chart types and describe how to use them most effectively in your dashboards, as well as pitfalls to avoid. In Part 1, we’ll discuss effective dashboard indicators. Part 2 will deal with basic charts and in Part 3 we’ll move on to charts that display more than one data element. In our final article, we’ll present some special purpose charts. With this collection of indicators and charts, your dashboards will stand head and shoulders above the competition, and leave your users with an unambiguous and actionable view of their data.
This category includes Line, Bar, Point, Linear Bubble, and Pie charts. These charts are simple to construct and very easy for users to comprehend, because they are used to display exactly one data element alongside one or more quantitative metrics describing that element. The Bar chart below displays the Product Brand for a supply chain company and two metrics describing that dimension, Total Cases Sold and Total Revenue. Depending on how much dashboard space is available, several additional metrics could have been displayed. Although this bar chart is displayed in a 3D format, it adds no additional information content but may slightly increase the visual impact of your dashboard. Don’t use fancy display options just because your BI tool provides them, ask yourself what, if any, additional benefit these options provide.
While Line and Point charts might appear to be interchangeable with Bar charts, these two charts are most effective when used to display time or date based dimensions. As with Bar charts, multiple quantitative metrics can be displayed in a single chart, provided that the chart does not get too crowded. In this example, the mean statistic is superimposed over each metric. This can be useful for alerting dashboard users when a particular metric has deviated too far from expected behavior, which can be either good or bad, depending on the metric. If statistics such as mean, median or regression lines are requested by end users or help to convey important information that is not immediately obvious by looking at the chart, then display it. If not, then don’t clutter your charts with it. Most importantly, make sure the statistic is valid – displaying a regression line through only 3 points is not only statistically invalid, it implies a trending relationship that probably does not exist. Don’t mislead your users by displaying erroneous information.
To download the complete four part series click here.