Central Tendency and Variability

When describing a specific population, central tendencies provide the most representative summary of observations collected, or sampled, from the target group of interest. Under ideal circumstances, population parameters, or the true population tendencies, would be known. However, computing these estimates would require having access to all members of the population, which is rarely feasible. Alternatively, sample statistics, or sample-based estimates of the population parameters, are computed in their place.

Measures of central tendency provide numerical estimates of the sample statistics. The statistics of central tendency and variability can be thought of as the basic characteristics of a sample. These estimates can be utilized to describe a sample as well as to statistically test inferences about population group membership, population subgroups, and group equivalences, among others.