<P> Recessions generally occur when there is a widespread drop in spending (an adverse demand shock). This may be triggered by various events, such as a financial crisis, an external trade shock, an adverse supply shock or the bursting of an economic bubble . Governments usually respond to recessions by adopting expansionary macroeconomic policies, such as increasing money supply, increasing government spending and decreasing taxation . </P> <P> In a 1979 New York Times article, economic statistician Julius Shiskin suggested several rules of thumb for defining a recession, one of which was two down consecutive quarters of GDP . In time, the other rules of thumb were forgotten . Some economists prefer a definition of a 1.5 - 2 percentage points rise in unemployment within 12 months . </P> <P> In the United States, the Business Cycle Dating Committee of the National Bureau of Economic Research (NBER) is generally seen as the authority for dating US recessions . The NBER defines an economic recession as: "a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production, and wholesale - retail sales ." Almost universally, academics, economists, policy makers, and businesses defer to the determination by the NBER for the precise dating of a recession's onset and end . </P> <P> In the United Kingdom, recessions are generally defined as two consecutive quarters of negative economic growth, as measured by the seasonal adjusted quarter - on - quarter figures for real GDP . The exact same recession definition applies for all member states of the European Union . </P>

Who declares when a recession starts and ends