Measures of central tendency are also know as measures of dispersion oflocation. Examples of central tendency are the mean, median, and mode.

The mode is best defined as the most frequently occuring data value. Forexample, the mode of the following data set [3, 7, 6, 8, 7] is 7.

The median is the number falling in the middle, when a data set is arrangedin ascending order. If there is an odd number of data items, the median is themiddle item in an ascending set of data values. If there is an even number ofdata items the median is the mean or average of the two middle data values. Forexample, since there is an odd number of data values in the following data setit is necessary to use the mean to determine the median; [10, 12, 14, 15, 15,15] median=14.5 (14+15)/2=14.5. Since only data in the middle of the set is usedto determine the median, outliers or extreme values do not affect the median.

A final measure of central tendency is the mean. The mean can be expressedas the average value in a data set. For example in the data set [3, 5, 7, 8,7] the mean is 6.