Mean, Median or Mode: Which Average Should You Use?

"Average" can mean three different things. On the same data they can give very different answers, and choosing the right one matters.

The three averages

• Mean: add up all the values and divide by how many there are.
• Median: the middle value once the data are sorted. With an even count, take the mean of the two middle values.
• Mode: the value that appears most often. There can be more than one, or none.

Example

Seven house prices on a street, in thousands: 210, 225, 230, 240, 250, 260, 900.

• Mean: 2,315 ÷ 7 ≈ 330.7
• Median: the 4th value, 240
• Mode: none, because every value appears once

One mansion pulls the mean far above what most of the houses cost. The median describes a "typical" house much better.

When to use which

• Mean: data without extreme values, such as class test scores, daily temperatures or repeated measurements. It uses every value.
• Median: skewed data or data with outliers, such as incomes, house prices or waiting times.
• Mode: categories or the most common choice, such as shoe sizes sold or the most popular survey answer.

Range and spread

An average alone hides how spread out the data are. The range (largest minus smallest) is a quick measure: 900 − 210 = 690 in the example. Standard deviation is a more robust measure of how far values typically sit from the mean.

Weighted mean

When some values count more than others, multiply each by its weight, add the results and divide by the total weight. Course grades and GPAs work this way.

Watch for "average" in headlines

If a report quotes an "average income", check which average it means. For incomes, the median is usually lower than the mean, because a few very high earners pull the mean up.