Are Sparklines Smart Lines?by Stacey Barr |
They’re so hot right now, sparklines. They thankfully bring some sanity to performance dashboards (goodbye goofy gauges). But they do have a limitation no-one seems to be talking about.
Sparklines are the crafty invention of statistician and data display guru Edward Tufte, and presented to the world in his book Beautiful Evidence.
A sparkline is a tiny line chart stripped down to its essential function of showing the time series of a specific measure. They are so tiny they can easily be embedded into text, tables and other tight spaces.
Little wonder Stephen Few has embraced them in his landmark book Information Dashboard Design.
I like them because you cannot manage performance when you’re looking at pie charts and gauges and dials. You need to see change over time.
What’s more, you need to separate the signals of change from the noisy variation that exists in any measure’s time series. And that’s where I think sparklines meet their limitation.
Sparklines still encourage you to focus too much on the first and last values of your performance measure, rather than the true signals of change that are based on the patterns in the time series, not the points.
Separating signals from noise, and drawing your eye to patterns rather than points, is something XmR charts do well. XmR charts are a specific type of statistical process control chart, discussed in detail (very interesting and readable detail) in Donald Wheeler’s book Understanding Variation.
They are graphs with 3 very important features that make performance measures so much easier to interpret validly.
I wondered what would happen if sparklines courted XmR charts? So I played with it and ended up with something that I reckon absolutely rocks. You get a tiny graphic that works well in text, tables and dashboards AND it is easier and faster and more valid to interpret what performance is really doing.
I call them ‘smartlines’. (I would like to call them ‘XmRtlines’, but pronounced ‘smartlines’ – too cryptic though, I think.)
What do you reckon, Stephen Few?
TAKE ACTION: Take the time to learn about XmR charts, and when you build your dashboards, give the smartlines (or XmRtlines) a go!
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