How to make graphs that work
1. Don't let popular spreadsheets be in charge of the way you look
92% of all the business presentations made in the United States are done with templates created by big companies in Excel or Powerpoint. This is a horrible tragedy.
First, programmers don't often have a lot of taste. The fonts are flaccid, the defaults are wan and uninspiring. There's no sophistication.
Second, and more important, when you show me something exactly like something I've seen a hundred times before, what do you expect me to do? Here's a hint: Zzzzzz.
2. Tell a story
There are only four reasons I can imagine you would want to show someone a graph (not a chart, or an infogram or a diagram, but a graph of numbers):
- Things are going great, look!
- Things are a disaster, help!
- Nothing much is happening.
- We need to work together to figure out what the data means.
I think if it's the third one, you can probably dispense with the graph altogether. And the fourth isn't really a presentation, it's a working session. Which means you're trying to light a fire, make a point, highlight a trend, cause action to be taken. Your graph should reflect that, or you're wasting my time.
3. Follow some simple rules
When you violate the fundamental rules of graphing, you confuse me, or cause me to pay attention to parts of your presentation that aren't related to the story you're trying to tell. Here are a few:
- Time goes on the bottom, and goes from left to right
- Good results should go up on the Y axis. This means that if you're charting weight loss, don't chart "how much I weigh" because good results would go down. Instead, chart "percentage of goal" or "how much I lost."
- Don't connect unrelated events. For example, a graph of IQs of everyone in your kindergarten class should be a series of unrelated points, not a line graph. On the other hand, your weight loss is in fact a continuous function, so each piece of data should be attached.
- Pie charts are spectacularly overrated. If you want to show me that four out of five dentists prefer Trident and that we need to target the fifth one, show me a picture of 5 dentists, but make one of them stand out. I'll remember that.
4. Break some other rules
Use color. Use thick lines. Use circles. Use big type faces. Don't use 3-D charts unless you have a license. You can animate, but only if you have a note from your doctor.
If you break too many rules, it'll backfire. If the graph is hard to grok, or appears tweaked too much, we cease to believe it. [and the Onion chimes in, ht to Tom]