Describe the major features of the business cycle. Be sure to discuss what variables are affected by the cycle, a description of the key features that are apparent in the data, how variables are related to one another, how regular the cycle is, and

how predictable the cycle is.

The business cycle is defined as a fluctuation of aggregate economic activity. There are recurrent but not periodic movements of aggregate activity, with many variables moving in the same direction at the same time (comovement). Increases in aggregate economic activity are expansions, while reductions in aggregate economic activity are contractions, or recessions. Both expansions and contractions exhibit persistence, so once an expansion or contraction begins, it tends to last some time.