The median of a set of data is that value from the data set that half of all measurements are above and half of all measurements are below. For example, in the data set below

4,9,2,5,10

Compare the median value to the average of a set of data. The average of the above data would be 6. In general, unlike the median the average of a set of data can be distorted easily by a few very large values: the average net worth of 5 Tech chemistry professors + Bill Gates would be on the order of 15 billion/person. Needless to say, the writer of this document does not have $15 billion. The median would be much closer to the actual net worth of Tech professors.

Example: What is the median of the following set of data? What is the average?

1.546,2.443,1.896, 1.499, 1.562, 1.689, 1.480

The median is just the middle value. If we put all the data in order

1.480, 1.499, 1.546, 1.562, 1.689, 1.896, 2.443

To get the average, sum all the numbers and divide by the number of data points (7)

average = (1.480+1.499+1.546+1.562+1.689+1.896+2.443)/7

average = 1.731

Information provided by: http://learn.chem.vt.edu