Median

The middle of the range of data: half the observations are less than or equal to it and half the observations are greater than or equal to it.  

If the data set contains an odd number of values then the median is simply the value in the middle of the ordered data set. In this set of numbers, the median is  three– two values are higher and two lower.

 

 

 

 

 

 

 

 

 

1

2

3

21

35

 

 

 

 

 

 

 

 

 

In a data set where there is an even number of values, take the average of the two middle values to arrive at the median. In this set of numbers contains an even number of values. Take the average of the two middle values (3 and 21) return a median value of 12.

 

 

 

 

 

 

 

 

1

2

3

21

35

42

 

 

 

 

 

 

 

 

Compared to the mean, the median is not sensitive to extreme data values, and is, thus, often a more informative measure of the center of skewed data.

For example, the mean may not be a good statistic for describing salaries within a company. The relatively high salaries of few top earners inflates the overall average, giving a false impression of salaries at the company. In this case the median is more informative.  The median is equivalent to the second quartile or the 50th percentile.