However, many empirical studies conclude that policy interest rates that were negative in real terms and deviated from  2  For example, considering 15 U.S. stock market crashes over the previous century, Mishkin and White (2002) find that not all resulted in economic contractions, and Bleaney and Castilla-Vargas (2009) demonstrate that currency depreciations during 1985–2004 were expansionary in developed markets.
Leamer (2007) uncovers a strong impact of housing crisis on output in the U.S. and Assmann et. al. (2009) estimate significant real effects of housing crises for a group of 15 industrial countries. 3  Reinhart and Rogoff (2009) pp. 158–162 examine the magnitude and duration of 21 downturns in housing prices that have accompanied major banking crises in both advanced and emerging economies.