Why Does the SRAS Slope Upwards?

Phillips Curve

Although the long-run aggregate supply curve (LRAS) is vertical at Y*, the equilibrium level of real output, the short-run aggregate supply curve (SRAS) is upward-sloping. Why?

Classical Misperceptions Theory

Output rises above Y* when the price level is higher than expected. The idea is that people confuse a rise in the general price level (to which they should not respond) with a rise in the relative price of what they produce (to which they should respond by increasing output).

Y = Y* + b(P - Pe)

Efficiency Wages

Real wages vary only slightly over the business cycle. According to the classical model, declines in employment during a recession reflect voluntary decisions by workers to work less in response to lower real wages.

• 1. much of the variation in employment over the business cycle is the result of involuntary layoffs in recessions and worker recalls in expansions

  2. when firms demand less labor, they generally lay off workers without lowering the wages of the workers they retain

reasons for real wage rigidity

• • legal and institutional barriers to cutting wages, e.g. minimum wage laws and union contracts

  • a wage cut during a recession may cause the more productive workers to quit so firms fire the poor workers instead

  • wage cuts are likely to reduce the effort of workers who remain with the firm

The efficiency wage model is based on this last idea: firms do not reduce wages in the face of persistent unemployment because to do so would reduce productivity. A worker's productivity might depend on the real wage for several reasons. First, lower paid workers are less loyal to the firm. Second, wage reduction makes the best workers quit. Third, lower wage reduce the costs of getting fired to employees so they do not work as hard and as efficiently.

If high wages increase workers' productivity by enough, it could be profitable for an employer to pay wages higher than the market clearing level. Paying high wages may also reduce the frequency of quits thereby saving firms the costs of hiring and training new workers. By reducing shirking and cutting supervision costs, a relatively high real wage may increase the employer's profits.

Efficiency wage theory helps to explain real wage rigidity. As long as the effort curve does not change, the employer will not change the real wage.

The level of employment depends only on labor demand. Labor demand depends on MPN. Let MPN* equal the marginal product of labor when worker effort is E*.

Employers know that workers working at wE will not put out as much effort per dollar of real wages as workers receiving w*. So, unemployment can continue indefinitely.

implications of efficiency wage theory

• • employment only varies when MPN* curve shifts

  • real wage is determined solely by effort curve

  • FE line is not affected by changes in the supply of labor

Menu Costs and Price Stickiness

Nominal price stickiness occurs when a price does not quickly change in response to changes in supply or demand. To account for the empirical non-neutrality of money, the classical model assumes that producers have imperfect information about the price level. If prices are sticky, they cannot adjust immediately to offset changes in the money supply so that money is not neutral.

The combination of monopolistic competition and menu costs provide a Keynesian explanation for nominal price stickiness. Menu costs include the physical costs of changing prices as well as the time taken to inform customers, the customer annoyance caused by price changes, and the effort required even to think about a price change. Monopolistically competitive firms have some power to set prices. They will not change their prices unless the profit-maximizing price and the existing price differ by enough to make it worthwhile to incur the menu cost to change the price. With prices fixed, firms adjust production to meet the demand for their output.

With any increase in aggregate demand, some firms will find it profitable to raise their price while others will increase output. So, the short run aggregate supply curve is upward sloping, and there is a different SRAS for each expected price level.

Money and Price Stickiness