Fed study--Rates should be negative 5%

The ideal interest rate for the US economy in current conditions would be minus 5 per cent, according to internal analysis prepared for the Federal Reserve’s last policy meeting.

The analysis was based on a so-called Taylor-rule approach that estimates an appropriate interest rate based on unemployment and inflation.

A central bank cannot cut interest rates below zero. However, the staff research suggests the Fed should maintain unconventional policies that provide stimulus roughly equivalent to an interest rate of minus 5 per cent.
http://www.ft.com/cms/s/0/37877644-32c9-11de-8116-00144feabdc0.html