The mean is affected by the extreme values of the observations in the data. This weakness of mean drives us to look for another average which is unaffected by a few extreme values. Median is one such a measure of central tendency.

Median is a measure of central tendency which gives the value of the middle-most observation in the data when the data is arranged in ascending (or descending) order.

Median of Raw Data

Median of raw data is calculated as:

  1. Arrange the data in an ascending (or descending) order.
  2. When the number of observations (n) is odd, the median is the value of (n+1)/2 observation.
  3. When the number of observations (n) is even, the median is the mean of the (n/2) and (n/2 + 1) observations.

Median of Ungrouped Data

Median of ungrouped data can be found from the cumulative frequency table (arranging data in increasing or decreasing order).