when are the mean and median different 
in a skewed data set the mean and median will typically be different the mean is calculated by adding up all of the values in the data and dividing by the number of observations if there are sizable outliers or if the data clumps around certain values the mean average will not be the midpoint of the data for instance in a set of data 0 0 0 1 1 2 10 10 the average would be 24 8 3 the median however would be 1 the midpoint value this is why many economists favor the median for reporting a nation s income or wealth since it is more representative of the actual income distribution the bottom linethe median is the number that lies in the middle of an ordered dataset that goes from lowest to highest it should not be confused with the mean which is determined by adding the numbers in a set together and dividing by the total number of data points many experts prefer using the median over the mean because it often provides a more accurate representation of the distribution in a data set 