“Average” can mean three different things. Choosing the right one changes the story your numbers tell. Try them on your own data with the average calculator.

Mean

Add all the values and divide by how many there are. Test scores of 70, 75, 80, 85 and 90 have a mean of 400 / 5 = 80.

Median

Sort the values and take the middle one. For an even count, average the two middle values. For 3, 5, 8, 12 the median is (5 + 8) / 2 = 6.5.

Mode

The most frequent value. In 2, 4, 4, 4, 7, 9 the mode is 4. A list can have no mode, or several.

Why the median is often better

Imagine five salaries: $45,000, $50,000, $52,000, $55,000 and $400,000. The mean is $120,400, which describes nobody. The median, $52,000, is much more representative. That is why Statistics Canada usually reports median income and why real estate boards report median home prices.

Range and standard deviation

The range is the highest value minus the lowest. The standard deviation measures how far values typically sit from the mean. Two classes can both average 75%, but one with a standard deviation of 3 is much more consistent than one with 15.

Quick guide