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Data slides: an example

May 22, 2010

Let’s look at an example and see how the 5 rules in the prior post can be applied to see if a slide works or not.

The slide below is a real one with minor alterations to protect the guilty.

Example powerpoint slide, bar chart

Example Slide 1A

At first glance it seems simple enough but by my count this slide breaks 4 of the 5 rules.  I’m pretty sure that when you glance at it you don’t see anything particularly wrong. But take a look at this:

Bar chart example with line across to highlight 150M

Example 1B

Now the issues are clearer. Clearly, there’s a conflict between the title of the slide and the data. Yes, literally the title statement “by 2012” is true, but the numbers say 150 million is exceeded in 2010. So why point out 2012? In fact, the data shows an expected drop in sales that year from a peak in 2011–so isn’t that the real point of 2012? A simple change in the title would fix that–refer to 2010. But that wouldn’t fix nearly all the issues here.

Another issue is the 3D nature of the bars. There’s no value to that and it’s a distraction–the brain processes what’s there and has to throw away the 3D effect–you wasted that effort that could have gone to understanding the data. While it’s not a big deal here, the 3D effect also makes it hard to see exactly what number each bar represents. In general, 3D effects should be avoided unless you’re dealing with 3D data or it somehow contributes to an understanding of the data. Here it is decoration and should be eliminated.

So let’s look at the rules as applied to this example:

Tell the truth. Marginal fail. The mismatch of title and data doesn’t tell a lie but it also fails to really identify what is true in the data.

Get to the point. Failed. If the point is in the title, the data failed to clearly support it. As a result I ask myself, what’s the real point of the chart: the data or the title?

Pick the right format for the data. Failed. The bar chart is correct, but the 3D effect is enough for me to score this as failed.

Highlight what’s important. Failed. If 2012 is the point, then that bar should be highlighted and it isn’t.

Keep it simple. Marginal pass. The chart seems simple but the flaws hurt it and make it confusing.

Clearly, this chart could be fixed with some simple changes. But as it appeared in the presentation it was a problem.  Someone (nope, not me) in the audience, in fact, asked about the 2010 vs. 2012 discrepancy. Once questioned at all, the presenter was then questioned about the 2011-to-2012 drop and they got flustered by the whole thing. They thought this was a really innocuous bit of data–and it should have been, but the chart hurt them not helped them.

It’s important to have data charts that support your point by being:

  • clear,
  • understood
  • and presented properly.

Getting them right isn’t easy, but applying the 5 rules data slides will help keep you on track and out of trouble!

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