1. the more formal term than average , when we cite the mean or average to describe the air temperature of summer, we know that there is substantial variation around this value, but that it nevertheless gives a reasonable expectation about what the weather will be like on any given day.
2. also called arithmetic mean , is the most frequently used measure of central tendency, calculated by dividing the sum of all values by the number of values in the data set.
Note: one shortcoming of the mean is that it is very sensitive to outliers or extreme values