By central tendency we refer to a stable value that (a) represents the signal in a
variable process and (b) is better approximated as the number of observations
grows.3 The obvious examples of statistics used as indicators of central tendency are
averages such as the mean and median. Processes with central tendencies have two
components: (a) a stable component, which is summarized by the mean, for
example; and (b) a variable component, such as the deviations of individual scores
around an average, which is often summarized by the standard deviation.