宏觀經濟/商業週期

商業週期

商業週期或經濟波動是總經濟活動中的起伏。商業週期由兩個階段和兩個轉折點組成。

1. Two Phases
 
 a. Expansion
  i. Time in which real GDP rises and unemployment declines.
  ii. Sometimes called recovery.
 
 b. Contraction
  i. Time in which real GDP declines and unemployment rises.
  ii. Recession - Six consecutive months of decrease.
   1. A "severe recession" is called a depression.
   2. No official definition of severe (length and depth).

2. Turning points
 
 a. Peak
  i. Real GDP reaches its maximum, stops rising, and begins to decline.
  ii. Determined after the fact.
 
 b. Trough
  i. Real GDP reaches its minimum, stops declining, and begins to rise.
  ii. Determined after the fact.

從一個高峰到下一個高峰，或從一個低谷到下一個低谷的序列是一個商業週期。收縮-低谷-擴張-高峰的模式一遍又一遍地出現，但並不是以規律的、可預測的時間間隔出現。