Interest rates and inflation part 3: Theory

This post takes up from two previous posts (part 1;  part 2), asking just what do we (we economists) really know about how interest rates affect inflation. Today, what does contemporary economic theory say? 

As you may recall, the standard story says that the Fed raises interest rates; inflation (and expected inflation) don't immediately jump up, so real interest rates rise; with some lag, higher real interest rates push down employment and output (IS); with some more lag, the softer economy leads to lower prices and wages (Phillips curve). So higher interest rates lower future inflation, albeit with "long and variable lags." 

Higher interest rates -> (lag) lower output, employment -> (lag) lower inflation. 

In part 1, we saw that it's not easy to see that story in the data. In part 2, we saw that half a century of formal empirical work also leaves that conclusion on very shaky ground. 

As they say at the University of Chicago, "Well, so much for the real world, how does it work in theory?" That is an important question. We never really believe things we don't have a theory for, and for good reason. So, today, let's look at what modern theory has to say about this question. And they are not unrelated questions. Theory has been trying to replicate this story for decades. 

The answer: Modern (anything post 1972) theory really does not support this idea. The standard new-Keynesian model does not produce anything like the standard story.  Models that modify that simple model to achieve something like result of the standard story do so with a long list of complex ingredients. The new ingredients are not just sufficient, they are (apparently) necessary to produce the desired dynamic pattern. Even these models do not  implement the verbal logic above. If the pattern that high interest rates lower inflation over a few years is true, it is by a completely different mechanism than the story tells. 

I conclude that we don't have a simple economic model that produces the standard belief. ("Simple" and "economic" are important qualifiers.) 

The simple new-Keynesian model 

Interest rates and inflation part 2: Losing faith in VARs

(This post continues part 1 which just looked at the data. Part 3 on theory is here) 

When the Fed raises interest rates, how does inflation respond? Are there "long and variable lags" to inflation and output?  

There is a standard story: The Fed raises interest rates; inflation is sticky so real interest rates (interest rate - inflation) rise; higher real interest rates lower output and employment; the softer economy pushes inflation down. Each of these is a lagged effect. But despite 40 years of effort, theory struggles to substantiate that story (next post), it's had to see in the data (last post), and the empirical work is ephemeral -- this post.  

The vector autoregression and related local projection are today the standard empirical tools to address how monetary policy affects the economy, and have been since Chris Sims' great work in the 1970s. (See Larry Christiano's review.) 

I am losing faith in the method and results. We need to find new ways to learn about the effects of monetary policy. This post expands on some thoughts on this topic in "Expectations and the Neutrality of Interest Rates," several of my papers from the 1990s* and excellent recent reviews from Valerie Ramey and  Emi Nakamura and Jón Steinsson, who  eloquently summarize the hard identification and computation troubles of contemporary empirical work.

Maybe popular wisdom is right, and economics just has to catch up. Perhaps we will. But a popular belief that does not have solid scientific theory and empirical backing, despite a 40 year effort for models and data that will provide the desired answer, must be a bit less trustworthy than one that does have such foundations. Practical people should consider that the Fed may be less powerful than traditionally thought, and that its interest rate policy has different effects than commonly thought. Whether and under what conditions high interest rates lower inflation, whether they do so with long and variable but nonetheless predictable and exploitable lags, is much less certain than you think. 

Blinder, supply shocks, and nominal anchors

An a recent WSJ oped (which I will post here when 30 days have passed), I criticized the "supply shock" theory of our current inflation. Alan Blinder responds in WSJ letters 

First, Mr. Cochrane claims, the supply-shock theory is about relative prices (that’s true), and that a rise in some relative price (e.g., energy) “can’t make the price of everything go up.” This is an old argument that monetarists started making a half-century ago, when the energy and food shocks struck. It has been debunked early and often. All that needs to happen is that when energy-related prices rise, many other prices, being sticky downward, don’t fall. That is what happened in the 1970s, 1980s and 2020s.

Second, Mr. Cochrane claims, the supply-shock theory “predicts that the price level, not the inflation rate, will return to where it came from—that any inflation should be followed by a period of deflation.” No. Not unless the prices of the goods afflicted by supply shocks return to the status quo ante and persistent inflation doesn’t creep into other prices. Neither has happened in this episode.

When economists disagree about fairly basic propositions, there must be an unstated assumption about which they disagree. If we figure out what it is, we can think more productively about who is right. 

I think the answer here is simple: To Blinder there is no "nominal anchor." In my analysis, there is. This is a question about which one can honorably disagree. (WSJ opeds have a hard word limit, so I did not have room for nuance on this issue.) 

Rangvid on housing inflation

(This post is an interlude between history and VARs) 

Jesper Rangvid has a great blog post today on different inflation measures. 

CPI and PCE core inflation (orange and gray) are how the US calculates inflation less food and energy, but including housing. We do an economically sophisticated measure that tries to measure the "cost of housing" by rents for those who rent, plus how much a homeowner pays by "renting" the house to him or herself. You can quickly come up with the plus and minus of that approach, especially for looking at month to month trends in inflation. Europe in the "HICP core" line doesn't even try and leaves owner occupied housing out altogether. 

Jesper's point: if you measure inflation Europe's way, US inflation is already back to 2%. The Fed can hang out a "mission accomplished" banner. (Or, in my view, a "it went away before we really had to do anything serious about it" banner.) And, since he writes to a European audience, Europe has a long way to go. 

A few deeper (and slightly grumpier) points: 

Interest rates and inflation -- part 1

Today I begin a three part series exploring interest rates and inflation. (Part 2 empirical work, Part 3 theory) 

How does the Fed influence inflation? Is the recent easing of inflation due to Fed policy, or happening on its own? To what extent should we look just to the Fed to bring inflation under control going forward? 

The standard story: The Fed raises the interest rate. Inflation is somewhat sticky. (Inflation is sticky. This is important later.) Thus the real interest rate also rises. The higher real interest rate softens the economy. And a softer economy slowly lowers inflation. The effect happens with "long and variables lags," so a higher interest rate today lowers inflation only a year or so from now. 

interest rate -> (lag) softer economy -> (lag) inflation declines

This is a natural heir to the view Milton Friedman propounded in his 1968 AEA presidential address, updated with interest rates in place of money growth. A good recent example is Christina and David Romer's paper underlying her AEA presidential address, which concludes of current events that as a result of the Fed's recent interest-rate increases, "one would expect substantial negative impacts on real GDP and inflation in 2023 and 2024."

This story is passed around like well worn truth. However, we'll see that it's actually much less founded than you may think. Today, I'll look at simple facts. In my next post, I'll look at current empirical work, and we'll find that support for the standard view is much weaker than you might think. Then, I'll look at theory. We'll find that contemporary theory (i.e. for the last 30 years) is strained to come up with anything like the standard view. 

Here's the history of interest rates and inflation. We're looking to see if high real interest rates push inflation down. 

Fitch is right

(Updated to fix numbers.) Fitch is right to downgrade the US. Read the sober report. But there are a few other reasons, or emphasis they might have added. 

• The inflationary default. 

Inflation is the economic equivalent of a partial default. The debt was sold under a 2% inflation target, and people expected that or less inflation. The government borrowed and printed $5 Trillion with no plan to pay it back, devaluing the outstanding debt as a result. Cumulative inflation so far means debt is repaid in dollars that are worth 10% less than if inflation had been* 2%. That's economically the same as a 10% haircut.