This document discusses the concept and calculation of the mean as a measure of central tendency. It defines the mean as the sum of all values divided by the total number of items. It provides the formula for calculating the mean from both ungrouped and grouped data, using frequency tables. It gives an example of calculating the mean from an ungrouped data set and from a grouped frequency table using midpoints. It also describes a shortcut formula that can be used to calculate the mean from grouped data. Finally, it discusses when the mean is most appropriate to use, noting that it is the most reliable measure when accuracy is needed and when further statistical analysis will be done.