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.
Part 1 – Using Dashboard Indicators
Before deciding which indicator to use for displaying a particular data entity, it helps to classify indicators based on the information content they are capable of displaying. Binary indicators can only communicate two information states such as acceptable/unacceptable, below/above goal, problematic/normal. Categorical indicators take this a step further allowing the dashboard designer to encode an ordered set of categories such as poor, satisfactory, excellent. At the top of the information pyramid we find compound indicators that can communicate not only directionality and order, but actual quantities.
Since compound indicators typically display the most information per square inch of dashboard space, it might seem logical to use them as often as possible. But understanding your target audience plays an even more important role in choosing the appropriate combination of indicators. A simple binary indicator can motivate an assembly line machine operator to take immediate action far more effectively than an indicator formatted with numerical values. On the other hand, an operations manager may need to see actual quantities and historical context when making staffing decisions.
Dashboard indicators such as Gauges, Dials, Bullets, Plus/Minus indicators and Sparklines can be used to illustrate:
- actual performance versus goal
- current status compared to performance thresholds
- deviation from expected trend
- direction and magnitude from a benchmark value
Indicators also add context to tabular data views, providing a top-level summary for users who don’t require or have the time to examine additional detail data. Indicators can be designed to display both qualitative metrics, typically via the use of color or color intensity, as well as quantitative metrics which are encoded as numeric labels.
Alerts are a single shape whose color and/or direction changes based on whether the value is above or below a specified threshold.
Sparklines are compact, sparsely formatted line charts. Their purpose is to show the overall trend of the displayed data and to show the most recent (rightmost) data point in the context of its history. When stacked in a dashboard, Sparklines provide immediate and unambiguous trend comparisons among related data entities.
The following example combines Alerts with Sparklines to enhance the information content of the Outpatient Utilization table. The red Alerts are positioned immediately to the left of the text labels so that the entities requiring attention are clear to the user. Quantitative information can be gained by examining the numerical values to the right of the text labels, while the 12 month trend on the far right provides historical context for why the three flagged areas may be exhibiting problematic behavior.
Plus/Minus indicators display both magnitude and direction from a predefined baseline for a given metric. Color can be used to provide context. In this example, the arrow is displayed in green, rather than red, to signify cost reductions from $25M to $10M. If we were displaying a drop in profits instead, red would obviously be the appropriate color.
The Bullet indicator is a compact and highly customizable visual dashboard building block.
In its simplest form, the Bullet indicator displays a quantitative value and a horizontal scale. No additional context or threshold is displayed.
This version of the Bullet indicator adds additional context by displaying a threshold via the black vertical line, and also encodes a qualitative measure using color (satisfactory, unsatisfactory).
To download the complete four part series click here.