For those who work in dashboarding, you’ll know that it’s a constant struggle to provide real value and what the text books like to call “actionable insight”, meaningful information that executives can act on. We constantly strive to provide real context, something more than just a number on a gauge, and often the best way to do so is to provide trend information for the metrics displayed.
By now you’re wondering what the hell spark lines are, right? Well spark lines are the invention of data visualisation guru and author of “Information Dashboard Design” Stephen Fews of Perceptual Edge. (If you work in visual business intelligence / dashboarding and have never read Stephen’s work, shame on you!) Spark lines are Stephen’s preferred way to represent trend information and a good example can be seen below. The Spark lines are those wriggly lines you see in the third column.
So how can you get the look in Xcelsius?
- Use a line chart without titles
- Switch off the axis and labels
- Make your font as small as possible
- Leave the markers on or off according to your taste.
For an example of how it can look in Xcelsius, here’s a draft dashboard I did a few months ago that includes some spark lines.
Where’s the value? The AHT region not only shows the result for the chosen day but also gives an insight into recent performance. With the markers left on, the user can hover over any of the last 30 days and see which have been the best and worse days.
Ditto for the service level trend. With the markers left off but a second line representing a target added, it’s easy to see at a glance how often the metric results are above and below the desired target over a considerable period. This is a lot of valuable information in a small area but you take it a little further. You could save some screen real estate by combining the chart and gauge to display the trend underneath the arrow. A little imagination can go along way!
Hopefully both simple examples illustrate how using spark lines to display trending information can bring a new level of context and valuable insight to your dashboard.
Update (27-11-07): Oops, apparently spark lines are the invention of Prof. Edward Tufte!
Jim Bytes - Doing I.T. in Dublin! 