Here are some best practices for designing dials:
Keep the dial simple
The simpler you keep your dial, the easier it is to understand and the more useful it is. The person viewing the dial should be able to understand in 10 seconds or less what the dial is showing.
- Remember the “10 Second Rule” when creating dials.
- Choose a visualization that makes the data easy to understand.
- Display the information in a way that tells the story you want to tell, such as the comparison charts below.
Choose a Dial that Connects Viewer to Real-world Events
Choose a visualization that helps the viewer to see trends that can be easily connected to real-world events.
A good visualization of the data helps to explain relationships between types of data.
Don’t Overdo Visual Appearance
Don't make dials fancy just because you can. Communication matters more than visual appeal. It can be tempting to make a dial that looks neat, but it’s more important to make one that makes sense.
- Color is good, but don’t overuse it.
Use dials that provide visual cues and color changes based on the evaluation of an account value against thresholds (such as expenses over budget). It’s a good idea to use high contrast colors and even provide other visual cues: 1 in 12 men and 1 in 200 women have some form of color blindness.
Show a Trend and Current State Together
Provide users with a trend and a current state visualization together. Combining a trend and a current state visualization (such as the one below) lets users see that Expenses are over budget for the current month (red highlight) and also see that they are projected to be over budget for the rest of the year based on the current budget.
Pie Charts have Limited Applicability
Although visually appealing, pie charts have limited applicability.
Use pie charts only when all slices of the pie make up 100% of whatever is being measured. In addition, the number of slices displayed on the dial should be considered carefully. Too many slices can make the dial difficult to understand.
Narrow Focus with Filters or Base Periods
If you narrow a dial’s focus with filters or by specifying a base period, say that in the dial’s display title.
A dial’s focus may seem obvious while you are creating it, but if its title doesn’t explain that it always shows a particular time unit, for example, this may cause confusion later when a change to the unit or date in the Period Selector doesn’t affect the dial. Similarly, filtering a dial so that it shows only the top five sales people can be very helpful, but if the title is just “Sales,” viewers may not know what they’re looking at. Titles like “Operating Expenses by Quarter” or “Top 5 Salespeople This Month” may seem too obvious when you’re designing the dial, but they promote clarity. Too clear is better than not clear enough.