Infographics traffic in data, but readers can’t form opinions about issues and won’t feel well informed without having information for comparison. You need to think of all the variables potentially involved in any comparison you make, though. Otherwise, you run the risk of saying something misleading or inaccurate. You can avoid that mistake, however, by making sure you use the right comparison.

To give an example, say that you are creating an infographic on the U.S. education budget. Say the total is \$250 million. You want to put the U.S. budget into a global context. How does the \$250 million spent annually by the United States stack up against other countries?

If you found out that Japan spends only \$200 million annually, it would seem that America spends — and thus, by suggestion, also values — education more than Japan does, which is what this figure implies.

But is that really a fair comparison? After all, Japan’s population is about one-third that of the U.S. population. So, although the Japanese government spends less on education in absolute terms, it actually spends far more per person (per capita), which is shown in the following figure.

Always strive to use numbers that take context, such as a country’s population, into account. That way, the information you present to the reader offers real insight and doesn’t create a false picture. Using per capita information rather than absolute totals, for instance, is a great way to create a more accurate comparison between two countries, or states, or cities. You get the idea.

Many databases keep per capita figures. Even if they don’t, determining this data isn’t difficult. The formula is simply the amount in question divided by the population.

amount/population = amount per capita

Here’s a simple, real-life example to figure out the U.S. national gross domestic product (GDP), which is the total value of all goods and services produced by a given country.

Follow these steps to calculate a per capita figure:

1. Find the amount in question for which you want to find the per capita figure.

In this case, the U.S. GDP is \$15,600,000,000,000, according to the World Bank.

2. Determine the population of the given country, state, or city.

The U.S. population is 316,000,000, according to the U.S. Census Bureau.

3. Apply this formula:

amount/population = amount per capita

\$15,600,000,000,000/316,000,000 = \$49,367 per capita

So what story does this per capita figure have to tell, and why is it more revealing than absolute GDP? Well, America has by far the world’s largest GDP, but it has only the tenth highest per capita GDP. This means that relative to other countries, the American economy is not the strongest.

Without figuring out the right number to use and then employing a comparison, this story wouldn’t be at all evident.