Median | Statistics

The median is a measure of the central value, the middle value in a data set. The median is the middle observation when the values have been sorted from the lowest to the highest value, or vice versa.

If the number of observations is odd, there will always be only one median. If the number of observations is even, there will be two observations in the middle. The median when it is an even number of observations is calculated as an average value of the two observations in the middle. The median of the following data set is 5:

1 2 5 9 9

Properties for the median:
1. There is only one median in a data set.
2. The median is not affected by extreme values as the mean is.
3. The median can be derived from a frequency distribution with open classes.
4. The median can be produced for a data set with ordinal data, interval data or ratio data.