How to make a PowerPoint chart
More data does not equal more information.
Sooner or later, you’re going to be tempted to use actual data in a presentation. Powerpoint makes it easy, and it also tempts you to do it completely wrong. Here are some ideas to help.
The first question: What’s the point?
Yes, there needs to be a point. The only reason to include statistics in a slide is to advance an argument. Unless you work for the National Institute of Health, the chances that you’ll be asked to review raw data on a slide and try to figure out causation is slim indeed. (Though this is a really useful way to do research and analysis, most readers of this blog don’t get invited to meetings like that very often).
In this slide from Garr, we see too much data, poorly presented. Does the relationship of internet connectivity via cell phone in the UK vs. France have anything to do with why we’re here? I don’t think it does. My guess is that the purpose of this slide is to persuade the viewer that an enormous percentage of those in South Korean have access. The rest of the stats are certainly nice, and they add credibility, but the details are not just irrelevant to the audience, they are actually distracting.
My version looks like this:
I’ve made an assumption–my audience is in the US. I’m trying to teach them that in South Korea, a vastly larger percentage of the market has access to the internet via their cell phone (perhaps I’m pitching a VC on a South Korean internet venture). While China and the UK offer me juicy relative stats, the audience is in the US and they are ethnocentric… they understand the state of their own market.
There are several other things going on here are that are a bit more subtle. The first is that left to right bar charts are silly. The audience takes a lot longer to ‘get’ the idea that something that extends further to the right is better. UP, on the other hand, is always better.
Second, when dealing with percentages, you need to communicate that getting closer to 100% is incrementally more difficult. In other words, 40% is not twice as good as 20%. It’s actually ten times as good if you’re talking about some sort of networked device like a fax machine. In this case, I do that by drawing a picture of a cell phone. As you can see, the closer you get to 100%, the happier your psyche is. The US phone is clearly broken, the other two are pretty close to great.
Next question: How do I make it a verb?
PowerPoint isn’t a printout. It’s a presentation. As a result, you get to create action. Instead of just showing the slide I just showed you, I’d show this slide instead. Why? Because I want to set the baseline. I’d say, "As you probably know, about a third of all the cell phones in the US have access to the Internet. As a result, there are relatively few useful services available, and most cell phone users rarely if ever go online. It’s too slow, too clumsy and there’s not enough to do."
Two things have happened. First, I’ve made a simple statement of fact that is easy to gut check and probably believe. It becomes your fact at that point, not mine.
The second thing I’ve done, by leaving the left side of the slide blank, is create a little itch. You’re wondering what’s on the left. You’re waiting for the punchline. THEN I show you the slide with all three countries on it, and I can say, "When you have almost complete penetration, the entire game changes…"
And then we’re in. We’re on the same page, and you’re ready to hear my story. Remember, you don’t pay by the slide. I did a presentation yesterday… 154 slides in 54 minutes. And I didn’t even break a sweat.
Last thought and then I’ll let you go. You can also aggregate data. In fact, you’re expected to. Pie charts are a great example of how people go wrong.
Here’s a typical pie chart, showing traffic sources to a website:
It’s accurate. It shows more than a half a dozen places that traffic come from. It’s also useless. It’s ungrokable. It doesn’t have a point.
Here’s the same data, grouped to make a point. "We get our traffic from three sources, one dominates the other two, but only one of them is under our control in terms of our ability to scale it directly. So let’s talk about how we grow that slice."
By all means, give me the data. All of it. Just do it in a printout, and share it with us at the end of the presentation.