Descriptive Statistics

Mean

In statistics, the mean (also known as average) is a measure of "central tendency" (which is, loosly speaking, an indication of the "middle" of the variable). This is calculated simply as the sum of all the observations divided by the number of observations. There are other forms of the mean (e.g., the "geometric mean"), but these are hardly ever used in statistics.

e.g., Among our customers, the mean number of purchases is 79.4.

Although the analysis of means is very common in marketing research, the mean has one important drawback: It is sensitive to the presence of outliers. The greater the outlier, the greater the effect on the mean. To choose an extreme example, if LeBron James buys your product, adding his single household into your set of customers may greatly increase the mean of your customers' household incomes. That said, the effect of LeBron on the mean will be limited if you have MANY other customers.