Medium-term fluctuations and the “Great Ratios” of economic growth

Evidence for the OECD countries show that the “great ratios”, such as the unemployment rate, factor shares, Tobin's q, and the investment-capital ratio, fluctuate significantly on medium-term frequencies of 8-40 years duration. To explain these medium-term fluctuations, we establish a macro-dynamic model where the q-theory of investment is combined with sluggish real-wage adjustment in the labour market. In this framework, responses to shocks show persistence and amplification. A high degree of real-wage rigidity combined with a low elasticity of factor substitution leads to damped internal oscillations and hump-shaped impulse-response functions.