What is the median?

The median is the value that lies exactly in the middle of all observed and ranked values. Unlike the mean which is calculated from observed values the median is an actual value. Thus the mean equals 6,2 for the values 1, 2, 4, 8, 16. On the contrary 4 is the median of this distribution as two values are higher and two values are lower than 4. As the mean demands at least ratioscales, the median is applied in those cases where values can only be measured by ratingscales.