Trusty numbers and statistics might be misleading you. Credit: Blair Wang / Flickr Creative Commons
If you’re looking to buy a house in a new city, you might want to know the average home price, or the average income in the area. But the average (or mean) home price might not be that helpful — a handful of very expensive homes in the area could easily skew the average. So you might want to find the median home price. We talk with mathematician and author Eugenia Cheng about the difference between median and mean — and how we can avoid being misled by statistics.
- When we talk about averages, we usually think of finding the mean. That’s the sum of all of the numbers divided by the total number of people or things. It’s useful, but can be misleading. The median of a range of numbers is the one that’s right in the middle. It can be used to weed out outliers that skew the data.
- What would happen if the people who make the most money made even more? The mean income might increase, but the median would stay the same, with major implications for studying income inequality. “One number is never going to sum up an entire situation,” Cheng says, so we can’t make generalizations based only on averages — or even medians.
- Knowing the difference between mean and median can help us avoid getting duped. By understanding what each average represents, it’s easier to figure out what the data can tell us — and what it doesn’t.
- Eugenia Cheng takes a for the Wall Street Journal, explaining why individual prices rise when mean prices fall.
- Feeling bogged down by the mathematics of averages? Khan Academy .
- Bloomberg explains using mean and median incomes from Census data.