In their classic 1999 paper, "Monetary policy shocks: What have we learned and to what end?," Christiano, Eichenbaum, and Evans (CEE) investigate one of the most widely used methods for identifying monetary policy shocks of its time. Unfortunately, their approach is no longer viable, at least...

Historically, attempts to solve the liquidity puzzle have focused on narrowly defined monetary aggregates, such as non-borrowed reserves, the monetary base, or M1. Many of these efforts have failed to find a short-term negative correlation between interest rates and monetary policy innovations....