Long waves

In economics, Kondratiev waves (also called supercycles, great surges, long waves, K-waves or the long economic cycle) are supposed cycle-like phenomena in the modern world economy.

It is stated that the period of a wave ranges from forty to sixty years, the cycles consist of alternating intervals between high sectoral growth and intervals of relatively slow growth.

The Soviet economist Nikolai Kondratiev (also written Kondratieff) was the first to bring these observations to international attention in his book The Major Economic Cycles (1925) alongside other works written in the same decade. In 1939, Joseph Schumpeter suggested naming the cycles "Kondratieff waves" in his honor.

Two Dutch economists, Jacob van Gelderen and Salomon de Wolff, had previously argued for the existence of 50- to 60-year cycles in 1913 and 1924, respectively.

Since the inception of the theory, various studies have expanded the range of possible cycles, finding longer or shorter cycles in the data. The Marxist scholar Ernest Mandel revived interest in long-wave theory with his 1964 essay predicting the end of the long boom after five years, and in his Alfred Marshall lectures in 1979. However, in Mandel's theory, there are no long "cycles", only distinct epochs of faster and slower growth spanning 20–25 years.

In 1990, William Thompson at Indiana University has published influential papers and books documenting eighteen K-Waves dating back to 930 AD in China’s Song Province; and Michael Snyder wrote “It should be noted that economic cycle theories have enabled some analysts to correctly predict the timing of recessions, stock market peaks and stock market crashes over the past couple of decades.”

The historian Eric Hobsbawm also wrote of the theory: "That good predictions have proved possible on the basis of Kondratiev Long Waves—this is not very common in economics—has convinced many historians and even some economists that there is something in them, even if we don't know what." 

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