What is the Median?
The median is the middle value of a sorted data set. It divides the data in half: 50% of values fall below it, 50% above. Unlike the mean, it is not pulled by extreme values.
How to Find the Median
- Sort all values from smallest to largest
- If n is odd: the median is the value at position (n + 1) / 2
- If n is even: the median is the average of the values at positions n/2 and n/2 + 1
Worked Examples
Odd count — Data: 3, 7, 8, 12, 20 (n = 5, already sorted)
Middle position: (5 + 1) / 2 = 3rd value → median = 8
Even count — Data: 3, 7, 8, 12 (n = 4)
Two middle values (2nd and 3rd): 7 and 8 → median = (7 + 8) / 2 = 7.5
Why the Median Resists Outliers
Compare two similar data sets:
Set A: 10, 12, 14, 16, 200 → Mean = 50.4, Median = 14
Set B: 10, 12, 14, 16, 18 → Mean = 14, Median = 14
Replacing 18 with 200 leaves the median unchanged but raises the mean from 14 to 50.4. The median sees only the position of values in the sorted list — extreme values cannot pull it away from the centre.
When to Use the Median
Prefer the median when:
- Your data contains outliers (very high or low values)
- The distribution is skewed — e.g., household income, house prices, response times
- You want the value that splits the group 50 / 50
National income statistics, real-estate reports, and medical response times almost always use the median for this reason. Use the statistics calculator to compare both on your own data.