The aggregate supply curve shows the relationship between the price level and output. While the long run aggregate supply curve is vertical, the short run aggregate supply curve is upward sloping. There are four major models that explain why the short-term aggregate supply curve slopes upward. The first is the sticky-wage model. The second is the worker-misperception model. The third is the imperfect-information model. The fourth is the sticky- price model. The following headings explain each of these models in depth. As we move on to explore each of these four models, keep in mind that an upward sloping short run aggregate supply curve means that as the price level rises, output increases. This is the point of each of the following models.
The sticky-wage model of the upward sloping short run aggregate supply curve is based on the labor market. In many industries, short run wages are set by contracts. That is, workers are paid based on relatively permanent pay schedules that are decided upon by management or unions or both. When the economy changes, the wage the workers receive cannot adjust immediately.
Given that wages are sticky, the chain of events leading from an increase in the price level to an increase in output is fairly straightforward. When the price level rises, the nominal wage remains fixed because this is solely based on the dollar amount of the wage. The real wage, on the other hand, falls because this is based on the purchasing power of the wage. A higher price level means that a given wage is able to purchase fewer goods and services.
PARAGAPH When the real wage that firms pay employees falls, labor becomes cheaper. However, since the amount of output produced for each unit of labor is still the same, firms choose to hire more workers and increase revenues and profits. When firms hire more labor, output increases. Thus, when the price level rises, output increases because of sticky wages.
Let's summarize the chain of events that leads from an increase in the price level to an increase in output in the sticky-wage model. When the price level rises, real wages fall. When real wages fall, labor becomes cheaper. When labor becomes cheaper, firms hire more labor. When firms hire more labor, output increases.
The worker-misperception model of the upward sloping short- run aggregate supply curve is again based on the labor market. This time, unlike in the sticky-wage model, wages are free to move as the economy changes. The amount of work that an employee is willing to supply is based on the expected real wage. That is, workers know how many dollars they are being paid, the nominal wage, but workers can only guess at how much goods and services they can purchase with this wage, the real wage. In general, the higher the real wage, the more work that workers are willing to supply.