Mean (mathematics).

Mean (mathematics). Mean (mathematics), also known as the arithmetic mean, a value that helps summarize an entire set of numbers. A set's mean is calculated by adding the numbers in the set together and dividing their sum by the number of members of the set. For example, the mean of the set {3, 4, 8} is 5, calculated (3 + 4 + 8)/3 = 5. Similarly, the set {16, 13, 9, 2} has a mean of (16 + 13 + 9 + 2)/4 = 10. In examining large collections of numbers, such as census data, it is helpful to be able to present a number that provides a summary of the data. Such numbers are often called descriptive statistics. The arithmetic mean is probably the best-known descriptive statistic. The mean is often called the average, but it is actually only one of several kinds of averages, such as the median and the mode. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.