# Mean

**Mean** - An Average. The sum of a data set divided by the number of data points.

Use the mean to describe the middle of a set of data that *does not have an outlier*.

The mean and median each have advantages and disadvantages when used to describe data sets. The mean depends on the actual values in a data set, but the median is dependent only on the relative position of the values. Changing one data value does not affect the median, unless the data value is moved across the middle of the data set. But every change in a data value affects the mean. Thus, the mean is affected by a few extremely large or extremely small values outside the range of the rest of the data, but the median is not.

Advantages:

• Most popular measure in fields such as business and engineering. • It is unique - there is only one answer. • Useful when comparing sets of data.

Disadvantages:

• Affected by extreme values (outliers)

Also see Median