Read this chapter to examine factors that determine private investment and its link to output within the macroeconomy. Private investment plays an important role in the short run by influencing aggregate demand, and in the long run by influencing the rate of growth of the economy.
Investment adds to the stock of capital, and the quantity of capital available to an economy is a crucial determinant of its productivity. Investment thus contributes to economic growth. We saw in Figure 14.4 "The Choice between Consumption and Investment" that an increase in an economy's stock of capital shifts its production possibilities curve outward. (Recall from the chapter on economic growth that it also shifts the economy's aggregate production function upward.) That also shifts its long-run aggregate supply curve to the right. At the same time, of course, an increase in investment affects aggregate demand, as we saw in Figure 14.6 "A Change in Investment and Aggregate Demand".