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Real Business Cycle
Theory
Theory developed by Edward Prescott and
Finn Kydland (Nobel laureates 2004)
Real Business Cycle Theory

This theory argues that productivity shocks to the
economy are the primary cause of business cycles.

Productivity shocks propagate throughout the economy
and affect the production function, employment,
investment, as well as the spending and saving decisions
of consumers.

They are also referred to as real shocks or supply shocks.
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Deviations from trend in TFP

TFP may slowdown when no significant discoveries
that affect production take place.

Measured TFP can also slowdown as a result of bad
weather, or other exogenous events.

Changes in TFP growth are recurrent, and not
necessarily predictable. (TFP deviations from trend
are well described by a Markov process with
persistence.)
Is the theory consistent with the data?

Qualitatively yes, but the RBC impulse (TFP changes) falls
short of accounting for changes in GDP.
Propagation mechanism amplifies the
impact of a shock to TFP growth

Two immediate effects follow from a change in
productivity

Investment demand changes (which affects interest rates, capital
accumulation, and ultimately GDP).

Capital utilization may also be affected (although capital
utilization is also affected by other factors like energy price
changes)

The demand for labor –labor force utilization- changes (which
affects wages, hours worked, and ultimately GDP).
Propagation mechanism: Impact on
GDP larger than original TFP shock

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
demand and the demand for labor.
Real Business Cycle Theory

The interest rate falls.
Real Business Cycle Theory

The lower the 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.
Summary of RBC theory

Shocks to productivity growth are the main force
driving business cycle fluctuations (accounting for
2/3 of the total volatility).

Expansions and recessions are not necessarily caused
by market failures.

Policy implications: The role of the government is to
provide an environment that promotes TFP growth.
Direct government interventions to smooth the cycle
may be counter productive.