Christina Romer, former CEA chair, called for a monetary regime change several times between 2011 and 2013. It is now several years later and it appears we did finally get a monetary regime change. Unfortunately, it is not the kind of regime change Christina advocated and actually goes in the opposite direction. 

Christina called for the Fed to adopt a nominal GDP level target that would restore aggregate demand to its pre-crisis growth path. Instead, we got a regime change that has effectively lowered the growth rate and the growth path of aggregate demand. This regime change, in my view, is behind the apparent drop in trend inflation that Greg Ip recently reported on in the Wall Street Journal. 

It is not easy to change trend inflation--just ask Paul Volker--but the Fed and other forces seemingly accomplished just that over the past decade. Since the end of the crisis, the average inflation rate on the Fed's preferred measure of inflation, the core PCE deflator, has fallen to 1.5 percent The headline PCE deflator average has fallen to 1.4 percent over the same period. Both are well below the Fed's target of 2 percent. 

This persistent shortfall of inflation has received a lot of attention from critics, including me. Lately, some Fed officials are also beginning to see the inflation shortfall as more than a series of one-off events. Governor Lael Brainard's recent speech is a good example of this change in thinking with her acknowledgement that trend inflation may be falling.

Still, there is something bigger going on here that is being missed in these conversations about the inflation rate. A monetary regime change has occurred that has lowered the growth rate and growth path of nominal demand. Since the recovery started in 2009Q3, NGDP growth has averaged 3.4 percent. This is below the 5.4 percent of 1990-2007 period (blue line in the figure below) or a 5.7 percent for the entire Great Moderation period of 1985-2007. Macroeconomic policy has dialed back the trend growth of nominal spending by 2 percentage points. That is a relatively large decline. This first development can be seen in the figure below.

The figure above also speaks to the second part of this regime change: aggregate demand growth was not allowed to bounce back at a higher growth rate during the recovery like it has in past recessions. Historically, Fed policy allowed aggregate demand to run a bit hot after a recession before settling it back down to its trend growth rate.  This kept the growth path of NGDP stable. You can see this if the figure above by noting how the growth rate (black line) typically would temporarily go above the trend (red line) after a recession.  

Had macroeconomic policy allowed aggregate demand growth to follow its typical bounce-back pattern after a recession, we would have seen something like the blue line in the figure. This line is a dynamic forecast from a simple autoregressive model based on the Great Moderation period. This naive forecast shows one would have expected NGDP growth to have reached as much as 8 percent during the recovery before settling back down to its average. Instead we barely got over 3 percent growth. This is why NGDP has never caught back up to its pre-crisis trend path. 

Again, these two developments are, in my view, the real story behind the drop in trend inflation. And to be clear, I think both the Fed's unwillingness to allow temporary overshooting and the safe asset shortage problem have contributed to it. So this is a joint monetary-fiscal problem that has effectively created a monetary regime change.

So yes, we got a monetary regime change, but no it is not the one Christina Romer and most of us wanted.