An important issue here is the possibility that the natural real rate may have fallen very low or even gone negative; this could occur for various reasons such as low productivity or a slowdown in population growth, both of which are relevant for the euro area.
A protracted period of deleveraging in the euro area, similar to the one which occurred in Japan in the 1990s, could also have pushed the natural real rate down, even into negative territory,  9  See M. Draghi , 2015. “The ECB’s recent monetary policy measures: effectiveness and challenges”, Camdessus Lecture, International Monetary Fund, Washington DC, 14 May.