As with the geological epochs and archeological ages, human times become more epochal as they become more homogeneous within themselves and more differentiated from other periods, units, or types. In analysis of variance (anova) terms, the times become more epochal as the within-unit variance decreases and the between-type variance increases. Movement toward more epochal times is illustrated by phrases such as the “New York minute.” This metaphor for the fast pace of life in New York City (see Levine 1997; also see Chapter 4) is so effective because it violates a tacit understanding about minutes:
Epochs as ANOVA analogy. As the time becomes more distinct (increased between-unit variance and decreased within-unit variance), it resembles an epoch.
Epochs can also be described metaphorically.
Example: SBTF and "peace time"