A reply to Sumner
I figured that my previous post might stimulate an interesting debate on the relative merits of NGDP targeting. So far, I've only heard from Scott Sumner (see here). Scott thinks I'm wrong for many reasons. He lists 4, which I reply to here.
1. Government price indices don’t measure the prices that are of macroeconomic interest. For instance in the 6 years after the housing bubble peaked the US, BLS data shows housing prices rising by about 10%, while Case-Shiller showed a 35% decline. Housing is 39% of the core CPI. That’s a big deal.
The BLS data show housing prices rising by 10% after housing prices peaked? Not sure I understand this claim. I thought that the price of housing services entered into the CPI, not house prices directly. In any case, it would have been nice to have been provided with an alternative price index.
2. But even if the data were accurate, prices are the wrong variable, and models that suggest PLT is equivalent to NGDPLT are simply wrong. Indeed one of the strongest arguments for NGDPLT is that it does better when productivity growth is unstable. And productivity growth in America is unstable.
Scott, I hate to break this to you but: all models are wrong in the sense that they are abstract representations of reality. Perhaps you mean "wrong" in the sense that any model that displays such an equivalence necessarily does not fit the data? If so, what evidence do you have that supports this claim?
By the way, Miles Kimball, who has some kind words to offer your crowd, claims here that the NGDP target has to be adjusted for changes in productivity growth. But maybe you have some different model in mind? Where does this model live?
3. It’s also a mistake to draw a trend line on the assumption that the Fed is doing PLT at 2.09%, if it is not in fact doing PLT at 2.09%. Fitted trend lines trick the human eye, as I’ve discussed in previous posts. Do I have evidence that they were not doing PLT at 2.09%? Sure, lots of evidence. The Fed called for fiscal stimulus in late 2008 and early 2009, which would have been sheer madness if they had been doing PLT at 2.09%. As you can see from the graph, the price level was actually above target in 2008, suggesting an overheating economy. That strongly suggests the trend line is in the wrong place.
I am not sure why a call for "fiscal stimulus" in late 2008 and early 2009 would have been "madness." The PCE price-level peaked in July 2008 and fell sharply in late 2008 and early 2009 (largely reflecting the collapse in energy prices).
4. You might respond that the trend line sure looks accurate. Yes, but I could draw a different trend line that would look equally accurate from 1990 to 2008, and then show the price level below target after 2008. Who’s to say that’s not right? Indeed that trend line would be far more consistent with the Fed’s calls for fiscal stimulus, and complaints from Fed officials that demand has fallen short of their goals.
Unfortunately I don’t know how to add trend lines to St Louis Fred graphs. But here’s the graph I’m thinking of, from January 1990 to September 2008. If you assume the Fed was doing PLT during that period, and fit a trend line, I claim that the period after September 2008 would entirely lie below the trend line. That would be partly because the slope would be steeper, and partly because the trend PL would be higher in September 2008 than on Andolfatto’s graph.
Scott: here is the graph. First, I logged the data (natural log). Then I drew a trend line through the data beginning in Jan 2009 and ending in Jul 2008 (not Sep 2008 as you suggest, because I'm sure you meant Jul 2008, the month in which the PCE price level peaked). I then projected this trend line through the rest of the sample. Here is the result:
I can hardly see any difference.
If PLT and NGDPLT really were similar policies, then why does NGDP look far below trend since 2008, while the price level (according to Andolfatto, but I have my doubts) is right on trend?
That would be because the RGDP is below trend. And there are many reasons why RGDP may be below trend that are independent of the conduct of monetary policy.
1. Government price indices don’t measure the prices that are of macroeconomic interest. For instance in the 6 years after the housing bubble peaked the US, BLS data shows housing prices rising by about 10%, while Case-Shiller showed a 35% decline. Housing is 39% of the core CPI. That’s a big deal.
The BLS data show housing prices rising by 10% after housing prices peaked? Not sure I understand this claim. I thought that the price of housing services entered into the CPI, not house prices directly. In any case, it would have been nice to have been provided with an alternative price index.
2. But even if the data were accurate, prices are the wrong variable, and models that suggest PLT is equivalent to NGDPLT are simply wrong. Indeed one of the strongest arguments for NGDPLT is that it does better when productivity growth is unstable. And productivity growth in America is unstable.
Scott, I hate to break this to you but: all models are wrong in the sense that they are abstract representations of reality. Perhaps you mean "wrong" in the sense that any model that displays such an equivalence necessarily does not fit the data? If so, what evidence do you have that supports this claim?
By the way, Miles Kimball, who has some kind words to offer your crowd, claims here that the NGDP target has to be adjusted for changes in productivity growth. But maybe you have some different model in mind? Where does this model live?
3. It’s also a mistake to draw a trend line on the assumption that the Fed is doing PLT at 2.09%, if it is not in fact doing PLT at 2.09%. Fitted trend lines trick the human eye, as I’ve discussed in previous posts. Do I have evidence that they were not doing PLT at 2.09%? Sure, lots of evidence. The Fed called for fiscal stimulus in late 2008 and early 2009, which would have been sheer madness if they had been doing PLT at 2.09%. As you can see from the graph, the price level was actually above target in 2008, suggesting an overheating economy. That strongly suggests the trend line is in the wrong place.
I am not sure why a call for "fiscal stimulus" in late 2008 and early 2009 would have been "madness." The PCE price-level peaked in July 2008 and fell sharply in late 2008 and early 2009 (largely reflecting the collapse in energy prices).
4. You might respond that the trend line sure looks accurate. Yes, but I could draw a different trend line that would look equally accurate from 1990 to 2008, and then show the price level below target after 2008. Who’s to say that’s not right? Indeed that trend line would be far more consistent with the Fed’s calls for fiscal stimulus, and complaints from Fed officials that demand has fallen short of their goals.
Unfortunately I don’t know how to add trend lines to St Louis Fred graphs. But here’s the graph I’m thinking of, from January 1990 to September 2008. If you assume the Fed was doing PLT during that period, and fit a trend line, I claim that the period after September 2008 would entirely lie below the trend line. That would be partly because the slope would be steeper, and partly because the trend PL would be higher in September 2008 than on Andolfatto’s graph.
Scott: here is the graph. First, I logged the data (natural log). Then I drew a trend line through the data beginning in Jan 2009 and ending in Jul 2008 (not Sep 2008 as you suggest, because I'm sure you meant Jul 2008, the month in which the PCE price level peaked). I then projected this trend line through the rest of the sample. Here is the result:
I can hardly see any difference.
If PLT and NGDPLT really were similar policies, then why does NGDP look far below trend since 2008, while the price level (according to Andolfatto, but I have my doubts) is right on trend?
That would be because the RGDP is below trend. And there are many reasons why RGDP may be below trend that are independent of the conduct of monetary policy.
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