What do the very low real long-term interest rates reflect?

Very low real long-term interest rates (in OECD countries, globally), lower than potential growth, may reflect: Ex ante excess private savings over investment. For the OECD (not for the world of course), excess savings may also be represented by the current account balance; An insufficient fiscal deficit , that did not correct the excess private savings over investment; A shortfall in the supply of risk-free bonds relative to demand; The bias created by ultra-expansionary monetary policies and very low real short-term interest rates. A statistical and econometric analysis seems to show the dominant role of expansionary monetary polic ies : central banks’ choices seem to be the determinant factor in setting the level of real long-term interest rates.