Define median? What are the merits …

Median may be defined a the middle value in the data set when its elements are arranged in a sequential order, that is, either in ascending or descending order of magnitude. It concentrates on the middle or centre of a distribution.

According to Connor, "The median is that value of the variable which divides the group into two equal parts, one part comprising all parts greater, and the other values less than median."

According to Horace Secrist, "Median of a series is the value of the item actual or estimated when a series is arranged in order of magnitude which divides the distribution into two parts."

According to Croxton and Cowden, "the median is generally defined as the value which divides the distribution so that an equal number of items is on either side of it."

Merits:

1. The median is useful in case of frequency distribution with open-end classes.
2. The median is recommended if distribution has unequal classes.
3. Extreme values do not affect the median as strongly as they affect the mean.
4. It is the most appropriate average in dealing with qualitative data.
5. The value of median can be determined graphically where as the value of mean can not be determined graphically.
6. It is easy to calculate and understand.

Demerits:

1. For calculating median it is necessary to arrange the data, where as other averages do not need arrangement.
2. Since it is a positional average its value is not determined by all the observations in the series.
3. Median is not capable for further algebraic calculations. 
4. The sampling stability of the median is less as compared to mean.