Consideration of the causes and consequences of booms and busts demands a clear definition of just when these booms and busts occur and what they look like, for it is the “stylized facts” or interpretations about sinusoidal, or wavelike, deviations from trend measures of output, employment, wages, interest rates, and the like that provide the focus of what is to be explained. To complicate matters, according to the twentieth-century American economist Victor Zarnowitz, while “business expansions and contractions consist of patterns of recurrent serially correlated and cross-correlated movements in many economic . . . activities,” these alternations in business conditions are not really “cycles”
since they involve no unique periodicities-their amplitude, scope, and duration vary considerably over time. So the question of whether booms are even related to busts is an open one.