An average calculated by adding the value of the points in a data set and dividing the sum by the number of data points. For example, suppose one wishes to calculate the average income of a country with exactly five people in it, and their incomes are $25,000, $26,000, $43,000, $70,000, and $72,000. It is calculated as:
($25,000 + $26,000 + $43,000 + $70,000 + $72,000) / 5 = $47,200.
A limitation to the arithmetic mean average is that it can be overly affected by extremes in either direction. For example, if one of the five persons in the country earns $100 billion per year, the arithmetic mean average income would be in the billions and would not accurately count the other four citizens. For this reason, many analysts use the
median in conjunction with the arithmetic mean average. The arithmetic mean average is also called simply the mean.