Mean, median, and mode
| Measure | What it is | For 85, 92, 78, 92, 88, 74, 95 |
|---|---|---|
| Mean | Sum ÷ count | 604 ÷ 7 = 86.29 |
| Median | Middle value when sorted | 88 |
| Mode | Most frequent value | 92 |
| Range | Largest − smallest | 95 − 74 = 21 |
Which average should I use?
The mean uses every value, so a single very large or small number can pull it a long way. The median is the better summary for data with outliers, such as home prices or incomes. The mode is useful for the most common size, score, or answer.
Standard deviation
Standard deviation measures how spread out the numbers are. Use the population version when your list is the entire group, and the sample version when it's a sample from a larger group.
Frequently asked questions
How do I find the median of an even number of values?
Sort the values and average the two in the middle. For 2, 4, 6, 8 the median is (4 + 6) ÷ 2 = 5.
What if no number repeats?
Then there's no mode. If several values tie for most frequent, each of them is a mode.