9.5 How the ad/as model incorporates growth, unemployment, and  (Page 21/15)

The AD/AS model can convey a number of interlocking relationships between the four macroeconomic goals of growth, unemployment , inflation    , and a sustainable balance of trade. Moreover, the AD/AS framework is flexible enough to accommodate both the Keynes’ law approach that focuses on aggregate demand and the short run, while also including the Say’s law approach that focuses on aggregate supply and the long run. These advantages are considerable. Every model is a simplified version of the deeper reality and, in the context of the AD/AS model, the three macroeconomic goals arise in ways that are sometimes indirect or incomplete. In this module, we consider how the AD/AS model illustrates the three macroeconomic goals of economic growth, low unemployment, and low inflation.

Growth and recession in the ad/as diagram

In the AD/AS diagram, long-run economic growth due to productivity increases over time will be represented by a gradual shift to the right of aggregate supply. The vertical line representing potential GDP (or the “full employment level of GDP”) will gradually shift to the right over time as well. A pattern of economic growth over three years, with the AS curve shifting slightly out to the right each year, was shown earlier in [link] (a). However, the factors that determine the speed of this long-term economic growth rate—like investment in physical and human capital, technology, and whether an economy can take advantage of catch-up growth—do not appear directly in the AD/AS diagram.

In the short run, GDP falls and rises in every economy, as the economy dips into recession or expands out of recession. Recessions are illustrated in the AD/AS diagram when the equilibrium level of real GDP is substantially below potential GDP, as occurred at the equilibrium point E ₀ in [link] . On the other hand, in years of resurgent economic growth the equilibrium will typically be close to potential GDP, as shown at equilibrium point E ₁ in that earlier figure.

Unemployment in the ad/as diagram

Two types of unemployment were described in the Unemployment chapter. Cyclical unemployment bounces up and down according to the short-run movements of GDP. Over the long run, in the United States, the unemployment rate typically hovers around 5% (give or take one percentage point or so), when the economy is healthy. In many of the national economies across Europe, the rate of unemployment in recent decades has only dropped to about 10% or a bit lower, even in good economic years. This baseline level of unemployment that occurs year-in and year-out is called the natural rate of unemployment    and is determined by how well the structures of market and government institutions in the economy lead to a matching of workers and employers in the labor market. Potential GDP can imply different unemployment rates in different economies, depending on the natural rate of unemployment for that economy.