Averages: Mean vs. Median

Why the word 'average' can hide two very different numbers, and why the median often tells you more about a typical person.

When a news report says “the average household earns” a certain amount, it is quietly making a choice. The mean is what most people think of as the average: add up all the values and divide by how many there are. The median is the middle value: line everyone up from lowest to highest and pick the person standing exactly in the middle. Half are above the median and half are below. For many economic questions, these two numbers can be surprisingly far apart.

Why the two can differ

The mean is sensitive to outliers - values far higher or lower than the rest. A single enormous income pulls the mean upward, even though it changes nothing for everyone else. The median barely notices outliers, because it only cares about who is in the middle position.

Income and wealth are classic examples of a skewed distribution, meaning the values are bunched up at one end with a long tail stretching out the other way. Most people earn modest amounts, while a small number earn a great deal. In this kind of data the mean is usually noticeably higher than the median, because those few very large values lift it.

Five neighbours and one new arrival

Picture five neighbours who each earn 30,000 dollars a year. Both the mean and the median are 30,000 dollars. Now a sixth neighbour moves in who earns 3 million dollars. The total income of the street jumps to 3 million 150 thousand dollars, and dividing by six gives a mean of 525,000 dollars. The median, though, is still 30,000 dollars, because the middle of the line has not moved. Saying "the average person on this street earns over half a million dollars" would be true by one definition and badly misleading about anyone's actual life.

Which one should you listen for?

Neither number is wrong; they answer different questions. The mean tells you the total divided evenly, which is useful when you care about the whole pie, such as total spending in an economy. The median tells you about the typical person, which is usually more useful when you want to know how ordinary households are doing.

That is why many statistical agencies report median household income rather than mean household income when describing living standards. If you hear a figure called simply “average income,” it is worth asking which kind of average is meant. If a report mentions both, the size of the gap between them is itself informative: a big gap suggests that a small group at the top is pulling away from everyone else.

Hearing averages in the news

A few verbal clues help. “Typical,” “middle,” and “half of households earn less than” all point to the median. “Per person,” “on average,” or “total divided by” usually point to the mean. When a speaker says incomes “rose on average” while many people feel no better off, a rising mean with a flat median is often the explanation.

Assuming the average describes a typical person

A common mistake is hearing a high mean figure and concluding that most people are near it. In skewed data like income, house prices, or wealth, most people are actually below the mean. If you want to know about the typical case, the median is usually the better guide.

Key takeaways

The mean adds everything up and divides; the median is the middle value.
Outliers pull the mean strongly but hardly move the median.
In skewed data like income and wealth, the mean is usually higher than the median.
The median usually describes a typical person better.
When you hear "average," ask which average is meant.