Measures of Dispersion for Ungrouped Data
Median
The middle value when the data is put in order.
| English | Median |
|---|---|
| Bahasa Melayu | Median |
| 中文 | 中位数 |
How it is used
For 3, 7, 8, 11, 15 the median is the middle value, 8. For an even set 4, 6, 8, 10 it is the mean of the two middle values, (6+8)/2 = 7.
Where it shows up in SPM
In Measures of Dispersion for ungrouped data, where it is the second quartile Q2 needed for the interquartile range, and in Measures of Central Tendency. Paper 1 tests it as a quick reading from an ordered list.
Don't confuse it with
Open the chapter: Measures of Dispersion for Ungrouped Data →
Frequently asked questions
Must I sort the data before finding the median?
Yes, always. The median is defined by position, so the values must be in ascending or descending order first.
Reading the middle of an unsorted list is the most common mistake and gives the wrong answer.
How do I find the median for an even number of values?
Take the two middle values and find their average. For 4, 6, 8, 10 the middle pair is 6 and 8, so the median is (6+8)/2 = 7.
The median can therefore be a value that is not in the data set.