How it works
- Mean: the sum divided by the count.
- Median: the middle value once sorted; with an even count, the average of the two middle values.
- Mode: the value that appears most often.
- Range: largest minus smallest.
Standard deviation measures how spread out the numbers are around the mean. Use the sample version (dividing by n − 1) when your numbers are a sample from a bigger group, and the population version (dividing by n) when they are the whole group.
The median is often better than the mean for incomes or house prices, because a few very large values pull the mean up.