Ch. 14. The Business Cycle. –Different theories of the business cycle Keynesian Monetarist Real...

Ch. 14. The Business Cycle.

–Different theories of the business cycle•Keynesian•Monetarist•Real Business Cycle

–Origins of and the mechanisms at work during the Great Depression

• Business Cycle Patterns– The business cycle is an irregular and

nonrepeating up-and-down movement of business activity that takes place around a generally rising trend.

– http://www.nber.org/cycles.html– Recessions are getting shorter.– Expansions are getting longer.

http://www.nber.org/cycles.html

http://www.nber.org/cycles.html

The Role of Investment

• All theories of the business cycle agree that investment and the accumulation of capital play a crucial role.– Recessions begin when investment slows and

recessions turn into expansions when investment increases.

– Investment and capital are crucial parts of cycles, but are not the only important parts.

Cycle Patterns, Impulses, and Mechanisms

• The AS-AD Model– All business cycle theories can be described

in terms of the AS-AD model.– Two business cycle theories

• Aggregate demand theories• Real business cycle theory

Aggregate Demand Theories of the Business Cycle

– Three types of AD theories• Keynesian• Monetarist• Rational expectations

AD Theories of Business Cycle

• Keynesian Theory– Volatile expectations are the main source of

business cycle fluctuations.– Nominal wages are rigid downward, but not

upward.

• Keynesian Impulse– “Animal spirits” change radically in response

to a small bit of new information.– Expected future sales and expected future

profits, which changes investment.


• Keynesian Cycle Mechanism– Changes in “animal spirits” lead to change in

investment– AD shifts– a flat (or nearly so) SAS curve.– Changes in I have multiplier effects

• e.g. as income rises, consumption rises, causing AD to shift further to the right, etc.


– A Keynesian recession.

– Real wages and productivity should rise during a recession.


– A Keynesian expansion.

– Real wages and productivity should fall during an expansion.


• Monetarist Theory– fluctuations in the quantity of money are the

main source of business cycle fluctuations in economic activity.

• Monetarist Impulse– The initial impulse is the growth rate of the

money supply.


• Monetarist Cycle Mechanism– A change in the monetary growth rate that

shifts the AD curve combined with an upward sloping SAS curve.

– An increase in the growth rate • lowers interest rates and the value of the dollar,

shifting AD rightward • multiplier effects amplify the effect.

– A decrease in the monetary growth rate has opposite effects.


• Recession phase of Monetarist business cycle.

• Real wages and productivity should rise during a recession.

Aggregate Demand Theories of the Business Cycle

• Expansion phase of monetarist business cycle.

• Real wages and productivity should fall during an expansion.


• Rational Expectations Theories– New classical theory

• Unanticipated fluctuations in AD are the main source of economic fluctuations.

– New Keynesian theory • Unanticipated fluctuations in AD are the main

source of economic fluctuations but also leaves room for anticipated fluctuations in AD to play a role.


– A rational expectations business cycle recession.


– Rational expectations expansion.

Real Business Cycle Theory

– technological change creating random fluctuations in productivity is the source of the business cycle.

• The RBC Impulse– The impulse in RBC theory is the growth rate

of productivity that results from technological change.


• The RBC Mechanism– Two immediate effects follow from a change in

productivity• Investment demand changes• The demand for labor changes


– The capital and labor markets in a real business cycle recession.

Real Business Cycle Theory– A decrease in productivity lowers firms’ profit

expectations and decreases both investment and labor demand


– The interest rate falls.

Real Business Cycle Theory– The lower real interest rate lowers the return from

current work so the supply of labor decreases.

Real Business Cycle Theory• Employment falls by a large amount and the real wage rate

falls by a small amount. Labor productivity decreases.


• Money in RBC– plays no role in the RBC theory; – RBC theory emphasizes that real things, not nominal

or monetary things, cause business cycles.

• Cycles and Growth– The shock that drives the cycle in RBC is the same

force that generates economic growth.– RBC concentrates on its SR consequences: growth

theory concentrates on its long-term consequences.

The Great Depression

• In early 1929 unemployment was at 3.2 percent. • In October the stock market fell by a third in two weeks.• In 1930, the price level fell by about three percent and

real GDP declined by about nine percent.• Over the next three years

– real GDP declined 29%– price level fell 24%– Unemployment peaked at 25%– Major transfer programs nonexistent.


• The 1920s were a prosperous era but as they drew to a close increased uncertainty affected investment and consumption demand for durables.

• The stock market crash of 1929 heightened uncertainty.• The uncertainty caused investment to fall, which

decreased AD and real GDP in 1930. • Until 1930, the Great Depression was similar to an

ordinary recession.


• Why the Great Depression Happened– Some economists think that the decrease in

investment was the primary cause that decreased aggregate demand and created the depression.

– Other economists (notably Milton Friedman & monetarists) assert that inept monetary policy was the primary cause of the decrease in aggregate demand.


– Unprecedented number of bank failures – Bank failures led to bank panics and more

failures. – Huge contraction in the money supply that

was not offset by the Federal Reserve.– Difficult to borrow money.


• Can It Happen Again?– Four reasons make it less likely that another

Great Depression will occur• Bank deposit insurance • Fed as lender of last resort. • Taxes and government spending • Multi-income families

Ch. 14. The Business Cycle. –Different theories of the business cycle Keynesian Monetarist Real...

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