Did macroeconomics give up on explaining recent economic history?

The debate that continues about whether a Phillips curve still exists partly reflects the situation in various countries where unemployment has fallen to levels that had previously led to rising inflation but this time wage inflation seems pretty static. In all probability this reflects two things: the existence of hidden unemployment, and that the NAIRU has fallen. See Bell and Blanchflower on both for the UK.

The idea that the NAIRU can move gradually over time leads many to argue that the Phillips curve itself becomes suspect. In this post I tried to argue this is a mistake. It is also a mistake to think that estimating the position of the NAIRU is a mugs game. It is what central banks have to do if they take a structural approach to modelling inflation (and what other reasonable approaches are there?). Which raises the question as to why analysis of how the NAIRU moves is not a more prominent part of macro.

The following account may be way off, but I want to set it down because I am not aware of seeing it outlined elsewhere. I want to start with my account of why modern macro left the financial sector out of their models before the crisis. To cut a long story short, a focus on business cycle dynamics meant that medium term shifts in the relationship between consumption and income were largely ignored. Those who did study these shifts convincingly related them to changes in financial sector behaviour. Had more attention been paid to this, we might have seen much more analysis and more understanding of finance to real linkages.

Could the same story be told about the NAIRU? As with medium term trends in consumption, there is a literature on medium term movements in the NAIRU (or structural unemployment), but it does not tend to get into the top journals. One of the reasons, as with consumption, is that such analysis tends to be what modern macroeconomists would call ad hoc: it uses lots of theoretical ideas, none of which are carefully microfounded within the same paper. That is not a choice by those who do this kind of empirical work, but a necessity.

Much the same could apply to other key macro aggregates like investment. When economists ask whether investment is currently unusually high or low, they typically draw graphs and calculate trends and averages. We should be able to do much better than that. We should instead be looking at the equation that best captures the past 30 odd years of investment data, and asking whether it currently over or under predicts. The same is true for equilibrium exchange rates.

It was not just the New Classical Counter Revolution in macro that led to this downgrading of what we might call structural time series analysis of key macro relationships. Equally responsible was Sims famous paper 1980 ‘Macroeconomics and Reality’, that attacked the type of identification restrictions used in time series analysis and which proposed instead VAR methods. This perfect storm relegated the time series analysis that had been the bread and butter of macroeconomics to the minor journals.

I do not think it is too grandiose to claim that as a consequence macroeconomics gave up on trying to explain recent macroeconomic history: what could be called the medium term behaviour of macroeconomic aggregates, or why the economy did what it did over the last 30 or 40 years. Macro focused on the details of how business cycles worked, instead of how business cycles linked together.

Leading macroeconomists involved in policy see the same gaps, but express this dissatisfaction in a different way (with the important exception of Olivier Blanchard). For example John Williams, who has just been appointed to run the New York Fed, calls here for the next generation of DSGE models to focus on three areas. First they need to have a greater focus on modelling the labour market and the degree of slack, which I think amounts to the same thing as how the NAIRU changes over time. Second, he talks about a greater focus on medium- or long- run developments to both the ‘supply’ and ‘demand’ sides of the economy. The third of course involves incorporating the financial sector.

Perhaps one day DSGE models will do all this, although I suspect the macroeconomy is so complex that there will always be important gaps in what can be microfounded. But if it does happen, it will not come anytime soon. It is time that macroeconomics revisited the decisions it made around 1980, and realise that the deficiencies with traditional time series analysis that it highlighted were not as great as future generations have subsequently imagined. Macroeconomics needs to start trying to explain recent macroeconomic history once again.

Reform and revolution in macroeconomics

Mainly for economists

Paul Romer has a few recent posts (start here, most recent here) where he tries to examine why the saltwater/freshwater divide in macroeconomics happened. A theme is that this cannot all be put down to New Classical economists wanting a revolution, and that a defensive/dismissive attitude from the traditional Keynesian status quo also had a lot to do with it.

I will leave others to discuss what Solow said or intended (see for example Robert Waldmann). However I have no doubt that many among the then Keynesian status quo did react in a defensive and dismissive way. They were, after all, on incredibly weak ground. That ground was not large econometric macromodels, but one single equation: the traditional Phillips curve. This had inflation at time t depending on expectations of inflation at time t, and the deviation of unemployment/output from its natural rate. Add rational expectations to that and you show that deviations from the natural rate are random, and Keynesian economics becomes irrelevant. As a result, too many Keynesian macroeconomists saw rational expectations (and therefore all things New Classical) as an existential threat, and reacted to that threat by attempting to rubbish rational expectations, rather than questioning the traditional Phillips curve. As a result, the status quo lost. [1]

We now know this defeat was temporary, because New Keynesians came along with their version of the Phillips curve and we got a new ‘synthesis’. But that took time, and you can describe what happened in the time in between in two ways. You could say that the New Classicals always had the goal of overthrowing (rather than improving) Keynesian economics, thought that they had succeeded, and simply ignored New Keynesian economics as a result. Or you could say that the initially unyielding reaction of traditional Keynesians created an adversarial way of doing things whose persistence Paul both deplores and is trying to explain. (I have no particular expertise on which story is nearer the truth. I went with the first in this post, but I’m happy to be persuaded by Paul and others that I was wrong.) In either case the idea is that if there had been more reform rather than revolution, things might have gone better for macroeconomics.

The point I want to discuss here is not about Keynesian economics, but about even more fundamental things: how evidence is treated in macroeconomics. You can think of the New Classical counter revolution as having two strands. The first involves Keynesian economics, and is the one everyone likes to talk about. But the second was perhaps even more important, at least to how academic macroeconomics is done. This was the microfoundations revolution, that brought us first RBC models and then DSGE models. As Paul writes:

“Lucas and Sargent were right in 1978 when they said that there was something wrong, fatally wrong, with large macro simulation models. Academic work on these models collapsed.”

The question I want to raise is whether for this strand as well, reform rather than revolution might have been better for macroeconomics.

First two points on the quote above from Paul. Of course not many academics worked directly on large macro simulation models at the time, but what a large number did do was either time series econometric work on individual equations that could be fed into these models, or analyse small aggregate models whose equations were not microfounded, but instead justified by an eclectic mix of theory and empirics. That work within academia did largely come to a halt, and was replaced by microfounded modelling.

Second, Lucas and Sargent’s critique was fatal in the sense of what academics subsequently did (and how they regarded these econometric simulation models), although they got a lot of help from Sims (1980). But it was not fatal in a more general sense. As Brad DeLong points out, these econometric simulation models survived both in the private and public sectors (in the US Fed, for example, or the UK OBR). In the UK they survived within the academic sector until the latter 1990s when academics helped kill them off.

I am not suggesting for one minute that these models are an adequate substitute for DSGE modelling. There is no doubt in my mind that DSGE modelling is a good way of doing macro theory, and I have learnt a lot from doing it myself. It is also obvious that there was a lot wrong with large econometric models in the 1970s. My question is whether it was right for academics to reject them completely, and much more importantly avoid the econometric work that academics once did that fed into them.

It is hard to get academic macroeconomists trained since the 1980s to address this question, because they have been taught that these models and techniques are fatally flawed because of the Lucas critique and identification problems. But DSGE models as a guide for policy are also fatally flawed because they are too simple. The unique property that DSGE models have is internal consistency. Take a DSGE model, and alter a few equations so that they fit the data much better, and you have what could be called a structural econometric model. It is internally inconsistent, but because it fits the data better it may be a better guide for policy.

What happened in the UK in the 1980s and 1990s is that structural econometric models evolved to minimise Lucas critique problems by incorporating rational expectations (and other New Classical ideas as well), and time series econometrics improved to deal with identification issues. If you like, you can say that structural econometric models became more like DSGE models, but where internal consistency was sacrificed when it proved clearly incompatible with the data.

These points are very difficult to get across to those brought up to believe that structural econometric models of the old fashioned kind are obsolete, and fatally flawed in a more fundamental sense. You will often be told that to forecast you can either use a DSGE model or some kind of (virtually) atheoretical VAR, or that policymakers have no alternative when doing policy analysis than to use a DSGE model. Both statements are simply wrong.

There is a deep irony here. At a time when academics doing other kinds of economics have done less theory and become more empirical, macroeconomics has gone in the opposite direction, adopting wholesale a methodology that prioritised the internal theoretical consistency of models above their ability to track the data. An alternative - where DSGE modelling informed and was informed by more traditional ways of doing macroeconomics - was possible, but the New Classical and microfoundations revolution cast that possibility aside.

Did this matter? Were there costs to this strand of the New Classical revolution?

Here is one answer. While it is nonsense to suggest that DSGE models cannot incorporate the financial sector or a financial crisis, academics tend to avoid addressing why some of the multitude of work now going on did not occur before the financial crisis. It is sometimes suggested that before the crisis there was no cause to do so. This is not true. Take consumption for example. Looking at the (non-filtered) time series for UK and US consumption, it is difficult to avoid attaching significant importance to the gradual evolution of credit conditions over the last two or three decades (see the references to work by Carroll and Muellbauer I give in this post). If this kind of work had received greater attention (which structural econometric modellers would almost certainly have done), that would have focused minds on why credit conditions changed, which in turn would have addressed issues involving the interaction between the real and financial sectors. If that had been done, macroeconomics might have been better prepared to examine the impact of the financial crisis.

It is not just Keynesian economics where reform rather than revolution might have been more productive as a consequence of Lucas and Sargent, 1979.

[1] The point is not whether expectations are generally rational or not. It is that any business cycle theory that depends on irrational inflation expectations appears improbable. Do we really believe business cycles would disappear if only inflation expectations were rational? PhDs of the 1970s and 1980s understood that, which is why most of them rejected the traditional Keynesian position. Also, as Paul Krugman points out, many Keynesian economists were happy to incorporate New Classical ideas. 

Simplistic theories of inflation

After I wrote this I saw that Frances Coppola has a post that covers some of the same ground, but the point I want to make is different.

One of the things that made monetarism so popular until governments actually tried it was its simplicity. You can express this simplicity in many ways, but most involve the idea that there is a stable demand for the real value of money (M/p), so if you can control M you must control p. Never mind that the immediate influences on inflation were much more complicated: if you knew what M was, you would know what p would be. If you controlled M you would eventually control p.

There are lots of problems with this idea. I talked about the difficulty in explaining prices by just using money in this post. The difficulty of finding the ‘right’ definition of money is not a technical problem but a feature: because money can be saved as well as buy goods (the medium of exchange is also a store of value) focusing on its role in buying goods (‘hot potatoes’) is misleading. But even if there was a stable long run demand for money for some definition, the usefulness of this becomes questionable if we cannot say what the future quantity of money will be.

This becomes blindingly obvious if money is base money and we think about Quantitative Easing. Printing base money under quantitative easing does not imply hyperinflation because the expansion in the monetary base will be reversed once the recession is over. Knowing what base money is becomes useless as a tool for saying what future prices will be. (For those more technically minded who still think there is a Pigou effect, I discussed why the Pigou effect has disappeared from modern macro here. It is based on the same point.)

The Fiscal Theory of the Price Level is potentially another simplistic theory of inflation. This works from the identity that the real value of government debt must equal the discounted value of primary surpluses (taxes less government spending). It also can be used in a naive way: treat future primary surpluses as fixed, and any increase in nominal government debt must lead to higher prices. But, as Chris Sims explains in this nice exposition at Lindau, future primary surpluses are not fixed. If debt increases, future primary surpluses can increase to pay the interest on that additional debt, and more.

There may be some that say that we cannot trust politicians to do that. To which I say which planet have you been on for the last five years? As Brad DeLong reminds us for the US, this recession has been unusual in the zeal that governments have shown in rapidly reducing primary deficits, and of course in the Eurozone this zeal - embodied in the fiscal compact - has led to a second recession. Chris Sims raised the possibility that so great has this zeal been that even though nominal debt has risen, the price level might fall to make the identity hold.

One lesson I would draw from this is that the Fiscal Theory of the Price Level, like monetarism, is not a terribly helpful way of thinking about future inflation. The idea that we can take one variable, or one equation, and distil from that the future price level is a fantasy. What is surprising is that this fantasy has been, and still remains, so attractive for some economists.

Fiscal backing

In an earlier post I went through the logic of why we do not think higher government debt necessarily causes inflation, even if that debt is denominated in nominal terms, as long as the central bank does not monetise that debt. As I argued there, talk of monetisation is largely unnecessary: we just need to say that the central bank uses interest rates to control inflation, and can therefore offset the impact of any increase in government debt.

However, as Mervyn King said, central banks are obsessed with budget deficits. This seems to contradict the previous paragraph. Are there some ways in which central banks would either lose the power to control interest rates, or be forced to abandon any inflation targets, as a result of fiscal policy? 

In the previous post the thought experiment I considered was a sustainable increase in the level of government debt. By sustainable I mean that the fiscal authorities raise taxes (or cut spending) to service this higher level of debt. But suppose they do not: suppose the budget deficit increases because spending is higher, but there is no sign that the government is prepared either to cut future spending or raise taxes to a sustainable level.

In 1981 Sargent and Wallace published a well known paper which said that, in this situation, the central bank could in the short term control inflation, but in the longer term inflation would have to rise to create the seignorage to make the government budget constraint balance. In other words, to keep the economy stable the central bank would eventually be forced to monetise. This was later generalised by the Fiscal Theory of the Price Level (FTPL). If the government did not act to stabilise debt itself (which Eric Leeper called – a little oddly - an active fiscal policy, and which others - including Woodford, Cochrane and Sims - have called even more confusingly a non-Ricardian policy [1]), then the price level would adjust to reduce the real value of government debt. Fiscal policy determines inflation.

One of the critiques of this theory is that the government budget constraint appears not to hold at disequilibrium prices. See, for example, Buiter here, and a response from Cochrane. I do not want to go into that now. Let’s also concede that if the monetary authority does either follow a rule that allows the price level to rise (by fixing the nominal interest rate for example), or tries to move interest rates to both stabilise debt and inflation (as in my recent paper with Tatiana Kirsanova), then the FTPL is correct.

The case I want to focus on here is where the central bank refuses to do either of those things, but carries on controlling inflation and ignoring debt. Suppose the government is running a deficit which is only sustainable if we have a burst of inflation which devalues the existing stock of government debt, but the central bank refuses to allow inflation to rise. You can say it does this by fixing the stock of money, or by raising the rate of interest - I do not think it matters which. This is an unstable situation: interest payments on the stock of debt at the low price level can only be paid for by issuing more debt, so debt explodes. In this situation, we have a game of chicken between the government and central bank.

Now the game of chicken would probably end when the markets refused to buy the government’s debt. That would be the crunch moment: either the central bank would bail the government out by printing money, or the government would default, which forces it to change fiscal policy. But in Buiter there is an elegant equilibrium outcome: the market just discounts the value of debt by an amount that allows the central bank to set the price level, but for the government’s budget constraint to hold at that price level. We get partial default. This discount factor becomes the extra variable that solves for the tension that both fiscal and monetary policy are trying to determine the price level.

You could quite reasonably suggest that such a central bank could not exist, because the government has ultimate power. It can always instruct the central bank to monetise the debt. However suppose the central bank actually managed the currency for a whole group of nations, and could only be instructed to do anything if they all agreed to do so. Furthermore that central bank was located in the one country in that group that would never contemplate monetisation, so it would be immune to pressure ‘from the street’. That central bank should be pretty confident it could win any game of chicken. [1]

Has any of this any relevance to today’s advanced economies? It seems to me pretty clear that these governments are not playing any game of chicken. Quite the opposite in fact: they are being far too enthusiastic in doing what they can to stabilise debt, despite there being a recession. So we certainly do not seem to be in a FTPL type world. Instead monetary policy right now retains fiscal backing.

Yet in a way we are having the wrong conversation here. Rather than trying to convince central banks that their fears are groundless, we should be asking whether monetary policy should – of its own free will – raise inflation to help reduce high levels of debt. I agree with Ken Rogoff that it should, and have argued the case here. Yet however optimal such a policy might be, the chances of it happening in today’s environment are nil. It looks like we may have to go through a lost decade before we are allowed to contemplate such things. 

[1] I guess a rationale for calling this fiscal policy ‘active’ is that stable regimes in Leeper require one partner to be active and the other passive. So in the normal regime monetary policy is active and fiscal passive, and this flips in a FTPL regime. In a FTPL regime, Ricardian Equivalence no longer holds (because taxes are not raised following a tax cut) – hence the label non-Ricardian.

[2] In this situation, would buying that government’s debt ‘show weakness’ in the game? If we follow Corsetti and Dedola and treat reserves as default free debt issued by the central bank rather than money, then not at all. Instead the central bank is giving the fiscal authority the best chance it can to put its house in order, by removing any bad equilibrium, but it retains the power to force default at any point. We no longer have Buiter’s method of resolving that game, but only because the central bank has the means which could force a win. As long as the government believes that the central bank would prefer the government to default rather than see inflation rise, the government should back down.