La Mediana

Median is one of the measures of the center. It is generally referred to as the middle value when the data are arranged in increasing or decreasing order. The median is denoted as x tilde. 

Consider sample data on the exam preparation time of college students. To find out the median value, first, arrange the data in decreasing order of preparation time. The number precisely at the center of the data is the median.   

What if there are even numbers of data values? There is no single middle value that can divide the data into two equal halves. In such a case, identify the two middle numbers. Then, determine the mean of these two numbers to arrive at the median. 

Unlike the mean, the median is a resistant measure of the center. The addition or removal of a few extreme values does not change the median by large amounts.

So, the median is a preferred measure of the center when the extreme values in a sample data set are unknown or not important.