Macroeconomics: Short-Run Fluctuations and Business Cycles
Foundations of Economic Fluctuations and Business Cycles
Economic fluctuations, also known as business cycles, refer to the short-run changes in the growth of real Gross Domestic Product (GDP). To analyze these cycles, economists typically compare the actual path of real GDP against a long-term trend line. Since the late 1920s, the United States economy has experienced fourteen distinct recessions. A recession is formally defined as a period of negative economic growth lasting at least two consecutive quarters. Recessions represent episodes where real GDP falls, and they are typically associated with severe socioeconomic consequences, including significant losses in employment, household income, and overall consumption. Conversely, an expansion is defined as a period of positive economic growth occurring between recessions. Historically, since 1929, a recession has occurred in the United States approximately once every six years, with the average duration of a recession lasting about one year.
Characteristics and Key Properties of Economic Fluctuations
Economic fluctuations are characterized by three primary features: co-movement of macroeconomic variables, limited predictability, and persistence. Co-movement refers to the tendency of many aggregate macroeconomic variables to grow or contract simultaneously during economic booms and busts. Variables such as real consumption, real investment, and employment exhibit positive co-movement, meaning they move in the same direction as real GDP. In contrast, unemployment exhibits negative co-movement, moving in the opposite direction of real GDP; as GDP falls during a recession, unemployment rises.
Limited predictability implies that recessions and expansions do not follow a repetitive or easily forecasted pattern. Consequently, it is nearly impossible to predict the exact timing of when an expansion will end or when a recession will transition into a recovery. Persistence refers to the fact that economic growth is not a series of random, independent events. Instead, the rate of growth tends to be self-reinforcing in the short term; if the economy is growing in one quarter, it is statistically likely to continue growing in the following quarter. Similarly, if the economy is contracting, it will likely continue to contract in the subsequent period.
Historical Overview of U.S. Recessions (1929–2020)
The history of the U.S. economy provides several illustrative examples of these fluctuations, most notably the Great Depression (1929–1940), the economic surge of World War II (1941–1945), the Great Recession (2007–2009), and the COVID-19 recession (2020). The following data details the duration and severity of U.S. recessions from 1929 to 2020, measured by the decline in real GDP from peak to trough:
- August 1929 to March 1933: Duration of 43 months; Real GDP decline of
- May 1937 to June 1938: Duration of 13 months; Real GDP decline of
- February 1945 to October 1945: Duration of 8 months; Real GDP decline of
- November 1948 to October 1949: Duration of 11 months; Real GDP decline of
- July 1953 to May 1954: Duration of 10 months; Real GDP decline of
- August 1957 to April 1958: Duration of 8 months; Real GDP decline of
- April 1960 to February 1961: Duration of 10 months; Real GDP decline of
- December 1969 to November 1970: Duration of 11 months; Real GDP decline of
- November 1973 to March 1975: Duration of 16 months; Real GDP decline of
- January 1980 to July 1980: Duration of 6 months; Real GDP decline of
- July 1981 to November 1982: Duration of 16 months; Real GDP decline of
- July 1990 to March 1991: Duration of 8 months; Real GDP decline of
- March 2001 to November 2001: Duration of 8 months; Real GDP decline of
- December 2007 to June 2009: Duration of 18 months; Real GDP decline of
- February 2020 to Unknown: Duration and total decline pending final data.
Macroeconomic Equilibrium and the Sources of Shocks
Economists agree that economic fluctuations are driven by unexpected shifts in labor demand, referred to as "shocks." At the onset of a recession, the labor demand curve shifts to the left. This shift is typically driven by three factors: a fall in output prices, a decrease in labor productivity, or a rise in input prices. When the labor demand curve shifts leftward, the quantity of labor demanded decreases, leading to a loss in employment. This reduction in employment directly results in a decrease in real GDP, as fewer workers are producing goods and services.
Schools of Thought on Economic Fluctuations
There are three prominent schools of thought regarding the primary sources of economic shocks. First, Real Business Cycle Theory emphasizes the role of technology and productivity. In this view, technological advances and productivity-enhancing innovations drive economic expansions, while increases in the price of essential inputs, such as oil, trigger recessions.
Second, Keynesian Theory focuses on the psychological factors of business and consumer expectations, famously termed "animal spirits" by John Maynard Keynes. These animal spirits reflect the general mood or sentiment of the public. A negative shock can generate widespread pessimism, causing a decrease in the willingness to spend. This decline in spending is often not offset by other sectors of the economy and is further amplified by multipliers.
Third, Financial and Monetary Theory, championed by Milton Friedman, focuses on changes in prices and interest rates. According to this theory, a decrease in the money supply () causes the general price level to fall. Because of downward wage rigidity (the tendency for wages not to fall even when labor demand decreases), a lower price level leads to reduced employment. Additionally, a drop in the money supply raises real interest rates, which discourages investment spending by firms.
Multipliers and the Process of Economic Contraction
Multipliers are mechanisms that amplify the initial impact of any economic shock. For instance, a negative consumption shock reduces the income of firms and their employees. This reduction in household income leads to even further decreases in spending, shifting the labor demand curve even further to the left. As the cycle continues, wages and employment fall toward the trough of the business cycle. Multipliers are exacerbated by several factors in a contracting economy, including falling asset prices (such as stocks or home values), a rise in mortgage defaults, and an increase in household and firm bankruptcies. During a short-run shock, the sequence typically moves from an initial leftward shift in labor demand to greater reductions caused by downward wage rigidity, and finally to massive shifts caused by the compounding effect of multipliers.
Economic Recovery in the Medium Run
While recessions are painful, several forces work to reverse their effects over the medium run, which typically spans a few years. These forces include market-based mechanisms and government policy interventions. Market forces that aid recovery include inventory rebuilding (as firms eventually must replace depleted stock), households returning to the market to resume spending, healthier firms purchasing the assets of bankrupt competitors, new technological advances, and the restoration of financial intermediation.
Government intervention primarily takes two forms: monetary and fiscal policy. Expansionary monetary policy, conducted by the central bank, involves lowering interest rates and raising inflation targets. Lower interest rates stimulate spending and investment, while inflation can reduce the real cost of labor if nominal wages are rigid, shifting the labor demand curve back to the right. Fiscal policy involves the government increasing its own spending or lowering taxes to put more disposable income into the hands of consumers and businesses. A full recovery is achieved when these forces shift the labor demand curve back to its pre-recession levels, moving the economy from the trough back to equilibrium employment and GDP.
Evidence-Based Economics: The Recessions of 2007–2009 and 2020
The Great Recession (2007–2009) was driven by three central factors: a collapse in housing prices (monitored by the Case-Shiller home price index), a subsequent sharp drop in residential investment and new construction, and a drop in household consumption. These were further complicated by spiraling mortgage defaults that led to bank failures and a freeze in the global financial system, exemplified by the collapse of Lehman Brothers.
The 2020 recession was unique as it was initiated by the COVID-19 pandemic. This event created a simultaneous demand and technology shock. On the demand side, consumers reduced spending due to concerns over their personal finances and the fear of infection. On the technology (supply) side, firms were forced to cut back activities because it became costly or impossible to operate safely during the pandemic. Data from the Covid Tracking Project and the Bureau of Labor Statistics show that during the first wave of the pandemic (March–May 2020), there was a sharp leftward shift in labor demand, leading to a massive spike in the unemployment rate.