Understand mean and median
Use a small example to see what the average and middle value each say about a group.
Follow the method ↓
The answer in 30 seconds
The arithmetic mean adds all observations and divides by their number. The median is the middle observation after sorting, or the mean of the two middle observations when the count is even.
For the illustrative values 2, 3, 4, 5 and 100, the mean is 22.8 while the median is 4. Report both when a very large or small value changes the picture, and describe what the values represent.
Examples to adapt
A few very high values can lift the mean above what most households pay.
A median may describe the middle experience while a mean captures total time divided across all cases.
Sample sizes, definitions and missing values matter as much as the chosen statistic.
Follow the method
- 1Define the observations
Check unit, period, sample and treatment of missing values.
- 2Compute the mean
Add the observed numbers and divide by their count.
- 3Compute the median
Sort the values and take the central value or the average of the two central values.
- 4Explain the difference
Look for skewed distributions and unusual values; show the count and range where useful.
A checklist to keep
Use these checks to record what you found. The grid supports a decision; it does not make one for you.
| Check | What to examine | Action |
|---|---|---|
| Data | Are observations comparable? | Define |
| Count | How many usable values? | Record |
| Mean | Sum divided by count? | Calculate |
| Median | Middle sorted value? | Calculate |
| Spread | Are extremes important? | Describe |
Free, no sign-up. UTF-8 text with semicolon-separated columns.
What to check
The median does not reveal the full spread of a distribution.
A single extreme value can substantially move the mean.
Different data definitions can invalidate a comparison even when the arithmetic is correct.
Common questions
Which statistic is always better?
Neither. Choose the measure that answers the question and show enough context to interpret it.
What is the median of four values?
Sort them and average the two central values.
Sources and documentation
Documentation consulted on . Examples are illustrative; interfaces and results may change.