The NAIRU: a response to critics

When I wrote my piece on NAIRU bashing, I mainly had in mind a few newspaper articles I had read which said we cannot reliably estimate it so why not junk the concept. What I had forgotten, however, is that for heterodox economists of a certain hue, the NAIRU is a trigger word, a bit like methodology is for mainstream economists. It conjures up lots of bad associations.

As a result, I got comments on my blog that were almost unbelievable. The most colourful was “NAIRU is the economic equivalent of "Muslim ban"”. At least two wanted to hold me directly responsible for any unemployment at the NAIRU. For example: “So according to you a fraction of the workforce needs to be kept unemployed.” Which is a bit like saying to doctors: “So according to you some people have to be allowed to die as a result of cancer.”

I have to say straight away that not everyone responded in that way. Some were much more thoughtful and constructive (like Jo Michell, for example). But the less thoughtful reactions are interesting in a way too.

I need to recap what the NAIRU is, particularly because heterodox economists seem to imagine it is many things it is not. Let’s take a very simple Phillips curve

Inflation this period = expected inflation next period - aU +b

where ‘a’ is a parameter and U is a measure of excess supply/demand in the economy. Unemployment will be one measure of that excess supply, but it is far from a perfect measure. (That my previous post was about excess supply, rather than actual unemployment, was obvious from what I wrote.) ‘b’ stands for a collection of slow moving variables. These could include a measure of union power, or how mobile labour was, or the degree of monopoly in the goods market. The NAIRU is defined as

NAIRU = b/a

If U is less than the NAIRU over a sustained period then inflation will rise, which will increase inflation expectations, which increases inflation further etc.

The concept is of interest to policymakers involved in demand management. They have to decide how much they can push demand before inflation starts rising. If they are independent central banks, they have to accept the world as it is. The NAIRU is a description of how the economy works: nothing more or less. This is why complaints that economists who use or estimate the concept are somehow responsible for those left unemployed are so dumb.

Of course you can criticise the concept of the NAIRU, but logically that has to involve criticism of the Phillips curve from where it comes. It is also reasonable to argue that the concept is fine, but the NAIRU is so difficult to measure that it would be better not to try and estimate it or let it guide policy. I have a lot of sympathy with that view at the moment, which is why I argue that, in the US right now, policy makers should find the NAIRU by allowing inflation to rise above target. But that point of view was irrelevant in my previous post, which was about the concept of the NAIRU, not its measurement.

As far as the concept is concerned, I think the strongest attacks come from thinking about hysteresis, as Jo Michell suggests. But even here, we add a complication to the NAIRU analysis, rather than overturn that analysis altogether. What hysteresis does is to make periods where unemployment is above the NAIRU extremely costly. It also means that periods of being slightly below the current NAIRU might be justified if they reduce the NAIRU itself.

I want to end by adding two reflections. The first relates to modelling the NAIRU. There once was, following the work of Layard and Nickell, an empirical literature that attempted to model for OECD countries a time series for the NAIRU, using proxy variables for things like union power, the benefit regime and geographical mismatch. With the dominance of the microfoundations methodology that work appears to have decreased, although to some extent it is still there in work based on matching models. I would be very interested to know if that time series analysis, now potentially enriched by matching models and flow data, has continued in any way.

The second relates to the sharp reactions to my original post I noted at the start, and the hostility displayed by some heterodox economists (I stress some) to the concept. I have been trying to decide what annoys me about this so much. I think it is this. The concept of the NAIRU, or equivalently the Phillips curve, is very basic to macroeconomics. It is hard to teach about inflation, unemployment and demand management without it. Those trying to set interest rates in independent central banks are, for the most part, doing what they can to find the optimal balance between inflation and unemployment.

Accepting the concept of the NAIRU does not mean you have to agree with their judgements. But if you want to argue that they could be doing something better, you need to use the language of macroeconomics. You can say, as many besides myself have done, that the NAIRU is either a lot lower than central bank estimates, or is currently so uncertain that these estimates should not influence policy. But if you say that the NAIRU has to be Bashed, Smashed, And Trashed, you will not get anywhere.

I also get very annoyed when I hear refutation by reference (as here for example). It would be so easy to write my blog posts that way. Instead I generally try to explain or present an argument that I hope is understandable. Economics is usually not so hard that this is impossible, although finding the right words is never easy. Economics is certainly not a religion, where all you have to do is choose which sect you belong to and then follow great works.     

Ann Pettifor on mainstream economics

Ann has a article that talks about the underlying factor behind the Brexit vote. Her thesis, that it represents the discontent of those left behind by globalisation, has been put forward by others. Unlike Brad DeLong, I have few problems with seeing this as a contributing factor to Brexit, because it is backed up by evidence, but like Brad DeLong I doubt it generalises to other countries. Unfortunately her piece is spoilt by a final section that is a tirade against mainstream economists which goes way over the top. Let me just go through the factual errors.

“Economists dictated the terms for austerity that has so harmed the British economy and society over the past ten years.”

The only support she gives for this statement is the 20 economists who signed a letter to the Times on 14th February 2010. She neglects to mention that 58 equally notable economists signed a response in the Financial Times on 18th February arguing the 20 were wrong. Austerity has always been a minority view among academic economists, a minority that has got smaller over time. Of course those that signed the first letter, and in particular Ken Rogoff, turned out to be a more prominent voice in the subsequent debate, but that is because he supported what policymakers were doing. He was mostly useful rather than influential.

“As the policies have failed, the vast majority of economists have refused to concede wrongdoing, nor have societies been offered alternatives.“

In the case of the 20 economists who signed that letter, nearly half did revise their views just two years later. More importantly, for the last few years pretty well every macroeconomist of note, including Ken Rogoff, has advocated a substantial increase in public investment. So this sentence, in so far as it relates to austerity, is almost as wrong as it could be

“[On Brexit} All the heavyweights of the economics profession … were wheeled out to warn the British people of economic facts known, and understood apparently, only to ‘experts’... But the ‘experts’ and the economic stories they tell have been well and truly walloped by the result of this referendum. And rightly so, because while there is truth in the story that international and in particular European cooperation and coordination are vital to economic activity and stability, there is no sound basis to the widely espoused economic ‘religion’ that markets—in money, trade, and labour—must be unfettered, detached from democratic regulatory oversight, and must be left to ‘govern’ whole countries, regions, and continents.”

Where did these heavyweights talk about “economic facts known, and understood apparently, only to experts”? When they were given the chance, they explained the common sense idea that trade would suffer if we left the EU because it is easier to trade with your neighbours, and the easy to understand empirical findings that more trade increases productivity and therefore economic growth. There is no religion involved at all, but rather statistical evidence. If you are looking for religion, you need to focus on the handful of economists supporting Brexit, who really did believe that it could usher in a neoliberal nirvana that would more than offset the costs of Brexit. To the extent that the public ignored the warnings of economists, it was probably because these warnings were ‘balanced’ in the media by this handful.

When Ann talks about the failings of economists related to the financial crisis she has a point, but it is one that she grossly exaggerates. Economists hardly “led the way to the re-regulation and ‘liberalization’ of the finance sector over the past 40 years”. The way was led by the financial sector itself. If more economists had backed up rather than dismissed Rajan’s warnings in 2005, I doubt if anything would have changed. Why do I think this? Because mainstream economists have subsequently argued that the only way to prevent another crisis is to substantially increase the capitalisation of banks, but they have been completely ignored by policymakers. If economists are being ignored after the financial crisis which created untold damage, why should things have been any different before the crisis?

I think the same point applies to globalisation. Most economists have certainly encouraged the idea that globalisation would increase overall prosperity, and they have been proved right. It is also true that many of these economists did not admit or stress enough that there would be losers as a result of this process who needed compensating from the increase in aggregate prosperity. But once again I doubt very much that anything would have changed if they had. And if they didn’t think enough about it in the past, they are now: see Paul De Grauwe here for example.

There is a regrettable (but understandable) tendency by heterodox economists on the left to try and pretend that economics and neoliberalism are somehow inextricably entwined. The reality is that neoliberal advocates do use some economic ideas as justification, but they ignore others which go in the opposite direction. As I often point out, many more academic economists spend their time analysing market imperfections than trying to show markets always work on their own. They get Nobel prizes for this work. I find attempts to suggest that economics somehow helped create austerity particularly annoying, as I (and many others) have spent many blog posts showing that economic theory and evidence demonstrates that austerity was a huge mistake.         

More on Stock-Flow Consistent models

This is a follow-up to this post, but which is prompted by this Bank of England paper, which builds a stock-flow consistent model for the UK. If you are not familiar with the term ‘stock-flow consistent’ (SFC) then read on, because in a sense this post is all about why I think the way the authors and others define this class of models is misleading.

SFC models are popular with Post-Keynesians, and the definition you find on Wikipedia is “a family of macroeconomic models based on a rigorous accounting framework, which guarantees a correct and comprehensive integration of all the flows and the stocks of an economy.” Now I suspect any mainstream macroeconomists would immediately respond that any DSGE model is also stock-flow consistent in this sense. This point is made in a post by Noah Smith, and it is completely valid, although otherwise I think his account of the weaknesses of SFC models is wide of the mark.

If you think this is a trivial debate about titles, take this description of the pros and cons of SFC compared to DSGE models taken from the paper:

Take the cons (merits of DSGE compared to SFC) first. Number one is almost definitional: DSGE models have to be microfounded, but SFC models start with aggregate relationships. But that is not a defining feature of SFC models, because there is a long tradition of macro modelling that is not microfounded but starts with aggregates, a tradition that begins well before DSGEs with the simultaneous creation of national accounts data, econometrics and Keynesian economics. This tradition goes by many names: ‘Structural Econometric Models’ (SEMs), ‘Cowles Commission’ (favoured by Ray Fair) or most recently ‘policy models’ (see Blanchard). I’ll just call them aggregate models here.

A key question, therefore, is what marks SFC models out from other aggregate models? The authors obviously think there is something, because of their second ‘con’. The third and fourth ‘cons’ are common to many large SEMs. (I once wrote a paper on how to mitigate the first of these problems.) The fifth ‘con’ just follows from the first.

At first sight the sixth ‘con’ does the same, but I would argue that if there is anything that characterises SFCs among aggregate models it is this. Aggregate models would generally involve an extensive discussion of the theoretical origins of the relationships they used, but if this paper is anything to go by that is less true for SFCs. If you think this last point is unfair, look at the discussion of the consumption function (before equation 4).

This failure to acknowledge the existence of other aggregate models is even more apparent among the ‘pros’. The first and second can be true for any model, including a DSGE model, but the third is critical. It is true, but again it is also true for many aggregate and some DSGE models. As I argue in my previous post, the key point about the archetypal DSGE model is that it does not need to track household wealth, because there is no attempt by consumers (given the theory) to achieve some target value of wealth.

The fourth is true for any model, including DSGE models. The fifth is true for any aggregate model as long as expections variables are explicitly identified. The sixth is also almost bound to be true of any aggregate model, because starting with aggregates and being eclectic (and potentially internally inconsistent) with theory allows you to more closely match the data than DSGEs.

To summarise, if you were to ask how this model compares to other aggregate (non-microfounded) models, the answer would probably be that it takes theory less seriously and it has a rather elaborate financial side.

The New Classical counter revolution had many good and bad consequences, but one of the undesirable consequences was, it seems, to define the equivalent of a year zero in macroeconomics, where nothing that was not in the New Classical tradition created before (or even after) this revolution is deemed to exist. The same should not be true for heterodox economists. If you are going to effectively return to a pre-DSGE tradition, please do not pretend that tradition did not exist.

There is a well known UK professor of econometrics who was very fond of admonishing authors who failed to cite work that they were either extending or just copying. The intention here is not just to do the same. One of the big dangers with any kind of elaborate aggregate model is that you can get bizarre model properties from not thinking enough about the theory, or imposing enough because of the theory. Knowing some of the authors I doubt that has happened in this case. But it would be a mistake for others to believe that the properties of their model show the importance of accounting rather than the theory they have used.