A statistician sees group features such as the mean and median as indicators of
stable properties of a variable system—properties that become evident only in the
aggregate. This stability can be thought of as the certainty in situations involving
uncertainty, the signal in noisy processes, or, the descriptor we prefer, central
tendency. Claiming that modern-day statisticians seldom use the term central
tendency, Moore (1990, p. 107) suggests that we abandon the phrase and speak
instead of measures of “center” or “location.” But we use the phrase here to
emphasize conceptual aspects of averages that we fear are often lost, especially to
students, when we talk about averages as if they were simply locations in
distributions.