Small things that make a big difference

Edward says: Use sparklines. Sparklines are data words. Or word graphics. A number without a history is boring. And can mislead. Even so, newspapers show lots of individual numbers. Deutsche Telekom’s revenues in the last quarter. The latest unemployment rate. Yesterday’s Dow Jones index. There’s room for a sparkline at the side. The size of a word. It shows nothing but the pattern of the values to date. You immediately understand it though. Whether it was higher some time in the past. Whether it’s been going up or down for a while. Whether it’s currently close to the historical high or low.

Here’s the development of the euro exchange rate compared to the US dollar. Since its introduction as book money on 1 January 1999 until today 1.32. Almost 3,000 values.

1. It’s not a sparkline without a number after it.

A sparkline is not simply a small time series. It needs the number after it. A sparkline doesn’t work without the number. If it’s there, we can see whether the previous numbers were totally different, slightly different, or more or less unchanged. We often don’t need to know things more precisely.

Wrong Right
Germany 37.7
France 130.4
Austria 75.1
Switzerland 56.6
Germany 37.7
France 130.4
Austria 75.1
Switzerland 56.6

You can add minimum or maximum to them if you wish. Or the initial value on the left.
You can’t write anything in the sparkline itself. Otherwise it will become larger than a word again.

2. The number belongs on the right.

The sparkline shows the number’s past. The number is the last point in the time series. That’s why the number belongs there. You should put things next to each other if they belong to each other. If a value’s on the left, you think it’s the first point in the journey through time. That’s why a sparkline’s number always belongs on the right.

The example shows how confusing it is if it’s done wrongly.

Wrong Right

Source: www.businessweek.com, retrieved 2006–12–12. Redesign: Me.

3. Scaling a sparkline impacts its meaning.

Careful! Scaling is important. Sparklines are small. Scaling is therefore very, very important. You often have several sparklines to compare. If you use the same scale for all of them, you are comparing the patterns and magnitudes of the series of values as well. That only works with similar values. If you use individual scales, you are merely comparing the patterns of the series of values. You compare the magnitudes using the numbers.

Scaled identically Scaled individually
South 9,786,026
North 2,812,324
East 743,415
West 140,476
South 9,786,026
North 2,812,324
East 743,415
West 140,476

Bars integrated in the table help you compare.

Scaled individually
South 9,786,026
North 2,812,324
East 743,415
West 140,476

4. Bars or lines?

Bars are easier to read. But they take up more space. I use bars for short time series, and lines for long ones. Mostly.

Short series Long series

5. Sparklines supplement figures, but do not replace them.

Sparklines are extremely nice in tables. Normally, tables show values for a point in time. Then you want to know how it was before then. So add sparklines. Sparklines can be used to incorporate the past of all values in nearly every table. But it’s wrong to omit the values altogether.

League table just with values

Wrong! Sparklines instead of values

Right! Sparklines and values

6. Sparklines like colors, but do not depend on them.

Publishers are still slightly afraid of sparklines. Especially of colored ones. Color printing is so expensive. But they don’t have to be in color. Sparklines work perfectly well without any coloring.

Single-colored

Now Min Max
Unemployment (1991–2009, in millions) 3.4 2.6 4.9

Multi-colored

Now Min Max
Unemployment (1991–2009, in millions) 3.4 2.6 4.9

SparkMaker helps you draw sparklines.