"The average salary in our team is £40,000." True, and also misleading. Here is why.

The team: eight people earn £30,000. The manager earns £120,000.

Mean

Add everything up and divide by the number of people: £360,000 ÷ 9 = £40,000.

One high value pulls it up. Nobody in this team actually earns £40,000.

Median

Line everyone up from lowest to highest and take the middle person: £30,000.

Much closer to what a typical person earns. Use it when a few values are very high or very low.

Mode

The most common value: £30,000.

Useful for categories, like the most common reason for a complaint.

Same data, fairer chart

Switch between the two versions of a chart about sign-ups.

Before

"Sign-ups up 50%!"

Bar chart with the axis starting at 3, so the second bar looks twice as tall.

After

"Sign-ups rose from 4 to 6."

Axis starts at 0 and the real numbers are on the bars. Small numbers, honestly shown.

Quick test

When you see a percentage, ask: "percentage of what?" If the starting number is small, the percentage can sound far bigger than it is.