Business cycle
Occurrence

Over the period since the Industrial Revolution, technological progress has had a much larger effect on the economy than any fluctuations in credit or debt, the primary exception being the Great Depression, which caused a multi-year steep economic decline. The effect of technological progress can be seen by the purchasing power of an average hour's work, which has grown from $3 in 1900 to $22 in 1990, measured in 2010 dollars. There were similar increases in real wages during the 19th century. (See: Productivity improving technologies (historical).) A table of innovations and long cycles can be seen at: Kondratiev wave § Modern modifications of Kondratiev theory. Since surprising news in the economy, which has a random aspect, impact the state of the business cycle, any corresponding descriptions must have a random part at its root that motivates the use of statistical frameworks in this area.
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