The business cycle or economic cycle refers to the periodic fluctuations of economic activity about its long term growth trend. The cycle involves shifts over time between periods of relatively rapid growth of output (recovery and prosperity), alternating with periods of relative stagnation or decline (contraction or recession). These fluctuations are often measured using the real gross domestic product. One of the government's main roles is to smooth out the business cycle and reduce its fluctuations.
To call those alternances "cycles" is rather misleading as they don't tend to repeat at fairly regular time intervals. Most observers find that their lengths (from peak to peak, or from trough to trough) vary, so that cycles are not mechanical in their regularity. Others see enough similarities between cycles that the cycle is a valid basis of studying the state of the economy. A key question is whether or not there are similar mechanisms that generate recessions and/or booms that exist in capitalist economies. Whether we can compare…
Traditional business cycle models
The main types of business cycles enumerated by Joseph Schumpeter and others in this field have been named after their discoverers or proposers:
1. the Kitchin inventory cycle (3-5 years) - after Joseph Kitchen.
2. the Juglar fixed investment cycle (7-11 years) -- after Clement Juglar.
3. the Kuznets infrastructural investment cycle (15-25 years) -- after Simon Kuznets, Nobel Laureate.
4. the Kondratieff wave or cycle (45-60 years) -- after Nikolai Kondratieff.
Even longer cycles are occasionally proposed, often as multiples of the Kondratiev cycle.
Juglar cycle
In the Juglar cycle, which is sometimes called "the" business cycle, recovery and prosperity are associated with increases in productivity, consumer confidence, aggregate demand, and prices. In the cycles before World War II or that of the late 1990s in the United States, the growth periods usually ended with the failure of speculative investments built on a bubble of confidence that bursts or deflates. In these cycles, the periods of contraction and stagnation reflect a purging of unsuccessful enterprises as resources are transferred by market forces from less productive uses to more productive uses. Cycles between 1945 and the 1990s in the United States were generally more restrained and followed political factors, such as fiscal policy and monetary policy.
Politically-based business cycle models
The partisan business cycle suggests that cycles result from the successive elections of administrations with different policy regimes. Regime A adopts expansionary policies, resulting in growth and inflation, but is voted out of office when inflation becomes unacceptably high. The replacement, Regime B, adopts contractionary policies reducing inflation and growth, and the downwards swing of the cycle. It is voted out of office when unemployment is too high, being replaced by Party A.
The political business cycle is an alternative theory stating that when an administration of any hue is elected, it initially adopts a contractionary policy to reduce inflation and gain a reputation for economic competence. It then adopts an expansionary policy in the lead up to the next election, hoping to achieve simultaneously low inflation and unemployment on Polling Day.
Preventing Business Cycles
Because the periods of stagnation are painful for many who lose their jobs, pressure arises for politicians to try to smooth out the oscillations. An important goal of all Western nations since the Great Depression has been to limit the dips. Government intervention in the economy can be risky, however. For instance, some of Herbert Hoover's efforts (including tax increases) are widely, though not universally, believed to have deepened the depression.
No one argues that managing economic policy to even out the cycle is an easy job in a society with a complex economy, even when Keynesian theory is applied. According to some theorists, notably nineteenth-century advocates of communism, this difficulty is insurmountable. Karl Marx in particular claimed that the recurrent business cycle crises of capitalism were inevitable results of the system's operations. In this view, all that the government can do is to change the timing of economic crises.
Problems of Measurement
Some argue that modern business cycle theory often measures growth by using the flawed measure of the economy's aggregate production, i.e., real gross domestic product, which is not useful for measuring well-being and also generates distortions in the perception of economic grow because the price changes of the various products are disproportional. Accordingly, there is a mismatch between the state of economic health as perceived by many individuals and that perceived by the bankers and economists, which most likely drives them further apart politically.
Business cycle theory has been most effective in microeconomics where it aids in the preparation of risk management scenarios and timing investment, especially in infrastructural capital that must pay for itself over a long period, and which must fund itself by cashflow in late years. When planning such large investments, it is often useful to use the anticipated business cycle as a baseline, so that unreasonable assumptions, e.g. constant exponential growth, are more easily eliminated.