The median is defined as the midpoint of a distribution: 50% of the values in a data set is either less than or equal to median and 50% of the values in a data is either greater than or equal to the median.

Also, given n terms the median is the $\frac{n+1}{2}$th value.

### Application

To calculate or find the median you have to find the point in the data set which divides the data set evenly into two equal parts. For small data sets this is easily done:

For example, finding the median of the following data set:

${7,2,5,1,3}$

Firstly, you have order them so they are in ascending order:

${1,2,3,5,7}$

Then you can see that the number ‘3’ divides the data set into two equal halves. 1,2 on one side and 5,7 on the other.

If however the the data set does not have an odd number of terms. You find the middle two terms of the set and take the average of the two values. For example, using the set before have have an extra value 9 added on the end so that we’re dealing with:

${1,2,3,5,7,9}$

To calculate the median is just the average if 3 and 5 which gives us the median to equal to 4.