The sum of the values of the points in a data set divided by the number of points.
HEIGHTS IN CENTIMETERS OF FIFTEEN CHILDREN ARE:
124, 137, 144, 136, 157, 129, 130, 131, 125, 128, 133, 133, 129
Sum equals 1995; divide by 15 to get the mean of 133.
In statistics, the mean refers to the value that results when all the scores in a data set are added together and the total is divided by the number of scores in the data set. In the example, the mean for a set of fifteen data points is calculated. The mean balances the scores on either side of it. Also called the arithmetic mean or average, the mean is one of the measures of central tendency; the others being the median and the mode.
Peavy, J. Virgil. Descriptive Statistics: Measures of Central Tendency and Dispersion. Atlanta, GA: U.S. Dept. of Health and Human Services/Public Health Service, Centers for Disease Control, 1981.