When the observation in the data are arranged in the order (ascending or descending), the median is the middle-value. That is 50% of the observations are below the median and 50% are above it.
Following are the steps to find the median of an ungrouped frequency distribution
Step 1. Arrange the variates in the ascending order of their magnitude.
Step 2. Find the total number of variates, say n.
Step 3. If n is odd then the median is the value of [(n+1)/2]th item. If n is even then the median is the A.M. of the values of (n/2)th and [(n/2) +1]th items.
1.) It can be calculated graphically.
2.) It is not affected by extreme values.
3.) It can be determined by inspection in many cases.
Demerits of the median
1.) It is not directly based on all the values.
2.) It is not as stable as the arithmetic mean.