2008 turned out to be the worst holiday shopping season in decades. Why? U.S. consumers were battered from many directions. Housing prices had fallen nearly 20% over the year. The stock market had fallen over 40%. Interest rates were falling, but credit was extremely hard to come by. By December, consumer confidence hit an all-time low amid concerns of rising unemployment. Cutting back seemed like the best defense for weathering this tough environment.

Consumption accounts for the bulk of aggregate demand in the United States and in other countries. In this chapter, we will examine the determinants of consumption and introduce a new model, the aggregate expenditures model, which will give insights into the aggregate demand curve. Any change in aggregate demand causes a change in income, and a change in income causes a change in consumption—which changes aggregate demand and thus income and thus consumption. The aggregate expenditures model will help us to unravel the important relationship between consumption and real GDP.