In the past, when I have advocated setting the central bank policy rate to zero and leaving it there several readers have suggested that this would set off uncontrollable asset price bubbles particularly in the housing sector. Indeed, the view among mainstream economists is that lax monetary policy in the US caused the sub-prime housing crisis. It is an intuitively attractive view for those who do not really understand how the monetary system operates and the complex distributional impacts that varying interest rates have. Today’s blog considers a US Federal Reserve research paper that has just been released which rejects the notion that “loose” monetary policy was to blame. It is an interesting research exercise.